You're hitting on a bunch of issues, and there isn't a single solution that resolves all of them.

4" line voltage cans max out at 50 watts, and even the best small 50w bulb doesn't make as much light as a low-end, larger 75w bulb (let alone a better large 75w bulb). You can find small low-voltage cans that will accept 75w MR16s, but each fixture will be much more expensive, and the light distribution isn't the same. As you've noted, LEDs bright enough to be useful for general illumination are still very expensive (and on the large side). I haven't seen a small LED bulb that can compete with incandescent, in terms of light output, at any price.

Between size, cost of fixtures and installation, light quality and long-term efficiency, you're wrestling with a bunch of competing priorities. You won't find the right solution until you figure out which are most important to you, and where you're willing to compromise.

Does anyone else have an opinion on the aesthetics of 4 vs. 5 vs. 6 inch recessed cans. My ceilings will be 10'high and I've been planning on using incandescent floods in 6" cans spaced 4' apart along the length of the great room on each side approximately 4' out from the side walls and an additional two down the middle between the seating and dining areas---a total of 14 cans on separate dimmers for general lighting. The great room (family room and dining room combined) is 32" long 18' wide. Now I'm afraid from reading the comments here that I'll have an unattractive UFO landing strip instead of a warmly lit space. Any opinions?

Just went through this same thing. 6" cans will be the least expensive for giving general lighting, but be sure to plan layers of light to give it a warm inviting look. Maybe a ceiling fixture can replace some of your cans? Sconces? I used the more expensive low volt for highlighting areas such as fireplace tile, art niche, bookshelves. Then had a central fancy light fixture/fan for architecture and hot days. Filled in with 6" can lighting. Then added decorative sconces on either side of the fireplace. This layering, plus dimmers will give your room warmth and set the atmosphere for the various ways you will use it without the commercial feel of all can lighting. Designers like to use the MR16s because the light has beautiful color, the bulbs come in a great variety of beam spreads, and various filters can be added. BUT they are spending someone else's money. Save these for where you want to add drama/impact--they really make crystal sparkle! I would avoid the line voltage 4" cans.

I am working on a plan similar to ginnytrcka - layers, layers and more layers. My architect spec'd approximately 175 -6"cans for our home. I've reduced it significantly and am supplementing by central fixtures and sconces. I am looking for a real traditional "older" home look and have a problem with cans in general. I am using 6" - I'd love to go smaller, but with 10' ceilings I don't think anything smaller will give off enough light. A friend of mine put in 4" cans for her kitchen and is really disappointed because she's not getting enough light.

Thanks folks. I am also trying to make my brand new home look like it has been there forever but just updated. At least that's my rationalization for putting in all the can lighting since it's so practical. Having a great room works wonderfully for our family but it does present a dilemma of getting light in the right places without stringing lamp cords everywhere. The lighting plan for the seating area now will be supplemented with lamps on a sofa table plugged into floor outlets and a ceiling fan with a light kit. In addition we'll do the mini lights to highlight the bookcase/fireplace wall. If this isn't sufficient I will have to add more table lamps around the room. The dining area will get a chandelier and 2 mini's over the table and wall sconces flanking the china cabinet.

Just as a side question: am I correct in believing that PAR light bulbs are all halogens? I keep reading about how 5" cans with PAR bulbs are all the rage. We live in Florida and I don't want anything that hot all over my ceiling, that's one of the reasons I've been thinking that 6" cans with incandescent floods will be the best thing for now (hate fluorescent lighting). Am I on the right track?

The 6" cans will give you the most flexibility in trims, though 5" has increased a lot. There are also converters to pop in 6" cans to change to par or even low-volt mr16 (has a transformer on it, the 6" can is big enough); the trim then narrows the hole to the smaller size. You would still have the larger trim size, but it can be painted. I didn't like the light from the 50w par bulbs; I was afraid it would be too dim. I like a really bright room most of the time and use dimmers to tone it down. But I have a friend who likes dark dramatic rooms and would never install as much light. The 6" cans are also easier to convert to fluorescent and the fluorescent bulbs have been really improving.