Greetings, Kimberlysc! You've come to the right place. I've "met" so many nice, helpful people on this site and helping seems to be something we all love to do.
First off, dig out your old Hosta on an overcast day or in the evening, if possible. Do not throw them away! Hosta can be divided into smaller clumps of new growth with a sharp spade or even a pruning saw. They actually prefer a shady location so if you have an area on the shady side of your mobile home that is not straight clay, plant them there with a generous dose of water to help them adjust. If it is straight clay, you'll need to add organic matter such as compost or seasoned (non-fresh) manure to the soil first.
Next, amend the existing soil in the spots where you took the Hostas out. Preparing the soil now will make things easier in the future! No matter what kind of soil is there, adding organic matter ALWAYS helps. It has some nutrient value and it will improve both a soil that doesn't drain well or one that doesn't hold water well. Either dig it in and mix it up with a spade or use a cultivator or rototiller to do the mixing for you. Rake smooth and allow to settle while you check out some local nurseries for perennials or shrubs.
Mobile homes tend to have a long, low appearance. If you like that look and want your planting to reflect that, purchase plants that will all grow to the same height. Personally, I think varying heights is much more interesting.
With regard to the shape of the garden, is it long and rectangular? Do you want it to stay that way? Would you prefer something more rounded to offset the long, low look of the home? If so, it's best to make those adjustments now so you'll have a better idea of how many plants you'll need to fill the space.
In terms of actual plants, how much maintenance do you want? Being a newbie, you probably want low maintenance so avoid shrubs that need to be pruned frequently to retain their size and shape.
I realize I've raised more questions for you to ponder but as you can see there's more to think about than just what plant is best.
Now for the short answer: Baptisia grows to a nice height, and spreads to about 2 1/2 to 3 ft wide. It has purple or white flowers on the more common varieties and tolerates most soils as long as they are not wet. In front of that you can put daylilies. Their long, strappy foliage will compliment the bapistia nicely and they come in a large variety of colors and bloom times. If you want a third, even lower-growing perennial to round out the planting, try Blue Spruce Sedum. The blue colored foliage will be great with the green-blue foliage of the Baptisia and the texture will add character.
Sandi

Transplanted has some great advice on soil prep. Definatly till in organic matter and even throw in some good potting soil. As for the beds, I personally would try to build in some curves to make it interesting. Perhaps curve your sidewalk to the front door if you haven't got one established, curve the beds, or even use some odd sizes and angles that accent the topography of your land. And I know it's extra work all year but I love having some nicely placed annuals for color. You have a huge varaity in the spring and summer, mums (perennial, fall blooming) in the fall and beautiful pansies in every color imagable in the fall and winter months. You can build the majority of your beds with perennials, then have small spaces left for the annuals. Throw in some inexpensive solar landscape lighting for accents after dark and perhaps a little accent with a nice gazing ball or statue. I'm dealing with much the same myself, I just built a ranch modular last year and am currently putting in the beds now. Have fun and good luck!! :-)

Greetings Sandi and Nannerbelle,
Thank you both for the advice. Sandi the soil we have in the front bed is actually very good. We added soil in the past. There's lots of clay in the yard but not in the front. I guess I'm old fashioned here. I'm use to the long and rectangular bed. With having the hostas and hydrangeas in the front you never had to do anything. The hostas came up in the spring, died in the winter, at which time the front bed was bare, I'm looking now to maybe having something year round. I would like color. I checked out the Baptisia, very very nice. Maybe putting plants that have some height in the back and the smaller plants in the front. I like annuals to. For the border I use to have the logs. They are ok, they just rot after a period of years. I want new plants and new borders. The solar lights are also a great idea. I have so much I would like to do. I have a husband that does not share in my joy of gardening so I am pretty well on my own. Between working on my garden and trying to plant some grass this fall I have my work cut out for me.

Good for you that you've already done soil work! If you can make it to a local swap, you may get some great plants for trades of your hostas, and lots of free advice.

If you want evergreen presence, you'll need to add something besides just the baptisia, sedum and daylilies. The sedum will have a small presence in winter but not much, and the others are below ground unless you choose to leave the seed pods on the baptisia. There are plenty of dwarf evergreens that could add some year round structure without a lot of trimming maintenance. Grasses can do the same, too, although many get pretty big. 'Little kitten' miscanthus comes to mind as a good one that would stay small but have great winter interest. The pennisetums work well, too. Honestly, i'd go to a garden center and see what appeals to your senses and tastes. Be sure to look at the mature size when choosing plants if you don't want to have to trim to maintain. You'll probably have to get fairly small plants to start, which is where the annuals will come in handy to fill in while you wait for the evergreens to fill in. Consider doing some annual vines on small trellises for height if you want some. There are also evergreen choices in vines (carolina jessamine is one) if you want a permanent trellis. Baptisia is a bit slow to gain size, but daylilies will size up fast.

I have to say, i'd add some curves, too, but if you like straight lines so be it. If you're redoing, though, be willing to at least think about changing it up- it's your perfect opportunity. Nature doesn't plant in straight lines, and it feels more natural to allow some movement, both vertically and horizontally. laying a hose down to make your line helps to visualize your new bed's edges. Then take spray paint or lime to mark along that edge. There's lots of edging options other than wood if you don't like replacing it every few years. Have fun designing you new area!

I'd look through the Niche Gardens and Bluestone Perennials website too -- Niche Gardens is in the piedmont of NC and has wonderful descriptions and brutally honest assessments of how plants perform in this area, and Bluestone offers a wide variety of plants for excellent prices. Bluestone sends small plants but they size up fast. Sunlight Gardens is another excellent mail-order nursery. I like mail order better than most local garden centers or big box stores because you can get a lot more natives and unusual plants that way. However, Niche Gardens and Plant Delights are both local nurseries for me so I also go there to shop and see their gardens.

Buddelia (butterfly bush) and tea roses are nice all-season plants. Tea roses (NOT hybrid tea) keep their leaves all winter and are pretty much disease free. Antique Roses Emporium, Roses Unlimited, Chamblee's, Vintage Gardens and Pickering are all excellent rose vendors. Blueberry bushes also make beautiful shrubs.