Go low voltage. Yes, they're more expensive, but you get more. They last longer, put out less heat, are more efficient and give better light than incandescent.

Don't forget that a 4" hole in your ceiling is visibly much nicer than a 6".

The low voltage halogen bulbs send most of the heat up, into the can. Line voltage bulbs send all the heat down... to the top of your head. That's why, if you look at the cans, the low voltage ones are much bigger- even though the bulb is so much smaller.
I have a low voltage halogen bulb which lasts 20,000 hours. That blows away any fluorescent.

And very soon there will be LED replacement bulbs/ modules for the low voltage fixtures.

I wouldn't combine the halogen with incandescent. The incandescent has a different color temperature and is bigger (and not as bright). And when you dim a halogen, the light becomes a very soft and inviting.

Keep in mind as well that an incandescent bulb continually emits less light. As the filament burns off and settles on the inside of the bulb (the black stuff you see), it blocks light. The halogen doesn't do that. The burned off filament keeps recycling back until it finally dies. That's how it lasts so long.
So at day one, the halogen is twice as bright. 2 years into it, the halogen can be 3 times as bright- simply because the incandescent is dimmer.

Thanks, lightguy. But can you comment on the difference between line-voltage halogen and low voltage halogen? They both have 3 to 4-inch diameter openings.

I have the same question. Line-voltage halogen is less expensive. Is there any reason to go with low voltage halogen now that line-voltage halogen is available in 3-4" diameter openings...