I have the same conditions only a little further north than you. I would never let the Hoopsii be the only blue spruce. Scatter some others around and tie the color theme together. I have 9 different cultivars of P. pungens in my yard and it isn't much bigger than yours. I have a 1/2 acre lot but that includes the horse barn and corral out back. Use one or two globes and perhaps a columnar blue spruce. I love 'St. Mary's Broom'. I have Picea pungens 'The Blues' and love it's weeping form. It will never get too big. I have a pendula out front and a little P. pungens 'Blue Pearl' in the same bed echoing the color theme as an accent. There are also a number of cultivars of P. omorika that won't get too big for your yard. Check out Coenosium Gardens web site for a wealth of ideas for the smaller yard. Much of what you find there will not be found locally though. You should be able to find what I mentioned above except perhaps 'Blue Pearl' or 'The Blues' Picea abies has an almost endless range of sizes and forms. I too covet the Skylands but have been afraid to give it a try with our dry heat in the summer and burning sun. If you try it I would certainly put it in an area where it isn't going to get full sun at least while getting established. I have put a P. abies 'Gold Drift' under a globe willow that will eventually come out -in hopes that it can get established in the shade and then show off it's gold color after the willow comes out. There are also some golden junipers that would work for you. The northern Utah nursery that I have found to have the best selection of the less common conifers is Alpine Gardens in Perry (south of Brigham City) but that is also a little hit and miss.

Where do you live? What kind of grass do you have? 80 degrees is not warm enough to cause a problem. What is your watering schedule? How often and for how long do you water? Top dressing with compost was the best advice available from the 1930s to the early 2000s. Now it is recognized by a growing number of people as the slowest and most expensive way to improve the lawn. Compost is a pile of depleted organic matter. If you want active organic matter, use a real organic fertilizer. Many people use Milorganite for several reasons. I like alfalfa pellets, soybean meal, corn meal, or corn gluten meal as raw organic fertilizer products available everywhere at your local feed store. Not all of those products will be available but one of them will be (alfalfa pellets are also rabbit chow). In my area the cost of compost delivered is about $75 per 1,000 square feet. Organic fertilizer is more like $5 per 1,000. Apply at a rate of 15 pounds per 1,000 square feet. You can use is safely as often as you can afford (every day or every month or every year). Here is a picture showing how organic fertilizer works. Mrmumbles posted that picture many years ago. He applied alfalfa pellets in mid May and took the picture in mid June. You can see the improved density, color, and growth. This picture has convinced lots of people to at least try organic fertilizer. Unless you live in a brick producing area, the topsoil your contractor used was unlikely to be clay. It might have been poor soil, but not clay. Only a soil test will tell. The best soil test lab in the US is Logan Labs in Ohio. Their $25 test will tell us and you all you need. Post the results here and get a good review of it. You might test both areas if you think the soil quality is considerably different from one to the other. In the mean time, spray your soil with 3 ounces of shampoo per 1,000 square feet. Use any clear shampoo - no additives like conditioners. Follow that with 1/2 to 1 inch of water and give it 3 weeks to take effect. After that when you water deeply or it rains, the soil should be noticeably softer to walk on. Do the fork or screwdriver test before and after to judge the effect. Test it several times. I did the test this weekend and got different results just a few inches apart. Once it is sprayed it should be soft when moist and very firm when dry between waterings. Adding new soil will not necessarily help. One problem with new soil is that it changes your drainage. You don't want to create a dam effect where the rainwater backs up into your house or basement. Water should drain away from the house for at least 10 feet. Another problem with new soil is that it will not be perfect, either. It will need the same $25 soil test to see what's wrong with it.

Making your own containers is entirely possible and redwood, cypress and cedar are quite rot resistant although they will not last forever. I would, though, offer some cautions. Rhododendrons are shallow rooted, but you need depth in a container to ensure drainage. I would not make any container less than 16" or so deep. A good depth of gravel would be much better than pavers. You want water to drain far away from the planting mix. Pooling on top of the pavers - unless they are porous - would be an invitation to water molds and other root rotting organisms. Everyone is tempted to provide enough space and planting mix to accommodate the adult plant. Don't do it. The roots of the young rhododendron will be surrounded by a mass of wet or at least moist planting mix that it cannot use. Organic material will be busily decaying, creating a mix that no longer drains well at all. As a general rule of thumb, there should be no more than 1-2" inches of space around the rim of a pot holding a rhododendron. This does require replanting every 2 or 3 years, but the planting mix itself needs replacement on pretty much the same schedule. I'm not at all familiar with what corner wedges are, but I gather you want to build a large box on top of the pavers. I think you would have much greater success using individual containers placed on gravel or another surface that would shed water immediately. There are commercially available containers that have better proportions for rhododendrons than the nursery can types. I have been using Panterra pots for some years. They have wide mouths and pleasing proportions and come in sizes up to 12" possibly 14" across. Of course, you can make boxes of size you want. It would also be a good idea to contact gardengal. She is a very knowledgable container grower who would be helpful.

PM - it's not just your opinion. Many growers with a good understanding of what it takes to consistently keep root systems healthy will opt either for a pot which allows generous gas exchange through the walls of the container, or they adopt grow media porous enough to allow gas exchange by way of diffusion from the top of the soil column to the bottom of the pot. The primary bias against pots with impermeable walls, including bonsai pots, is when used in combination with media that support excess water, gas diffusion essentially stops at the top of the excess (perched) water table. Gasses diffuse approximately 10,000 times faster in air than in water, leaving the fraction of the grow medium which is completely saturated little more than an anaerobic swamp that produces the same gasses as swamps, among them are CO2, methane, and hydrogen sulfide, all of which displace oxygen essential to root function/ health. Any pots with smooth sides, like glass/ plastic/ high-fired clay (porcelain), provide less anchorage than low-fired clay, unless they are shaped with a rim/ top opening that is smaller than the maximum diameter of the pot. IOW, a plant can become lodged almost inextricably in a pot with an 8" maximum diameter and a 6" top opening. These pot often must be broken in order to extract the plant at repotting time. Even dead woody plants in these pots are very difficult to remove w/o breaking the pot. Some inexpensive bonsai pots have drainage holes located higher than the lowest point on the pot. It might be surprising to learn that many bonsai growers will not plant valuable plants in pots which do not drain completely. That the holes in bonsai pots are often several and their size large for the pot size, have nothing to do with drainage insofar as how completely the soil drains. A pot with a 1/8" hole would drain as completely as a a pot with 4 - 3/4" holes, it might take a couple of minutes longer, but the net result would be the same. Finally, something true of every grow medium that supports perched water is, when the medium is at container capacity (holding all the water it can, the ht of the perched water table will be the same in any container, regardless of its height or shape. This image (already posted) illustrates that principle in pots of various hts ...... The pot on the left looks like about 80-90% of the soil column is free of perched water; while, using the same grow medium, less than 1/3 of the soil holds enough air to allow roots growing in that fraction of the medium to grow normally. This is why it is soo important to use well-aerated, fast-draining media in shallow pots. The containers below illustrate the shape of the pot doesn't affect the ht of the perched water table. Notice how simply tipping the pot (fig B) eliminated much of the water the planting is capable of holding. Use this when it's raining or immediately after a thorough watering. In fig C we see the shape of the container can significantly affect the VOLUME of perched water a planting can hold, but not the maximum ht of the perched water table. Fig D shows how using an over-turned as ballast inside of the main pot can significantly and passively reduce how much water a planting can hold. Al