Thanks Cheerpeople. :) I went out to the new house and they were painting, so it was looking like a "real" house now, which gave me a much better perspective. Armed with tape measure and my circle of cardboard, I determined the diameter is fine. But as justgotabeme was saying, what surrounds it makes a difference. The lights would be next to a short wall from the ceiling because the room behind it has pony walls and open walls. But the "pony" wall continues at the ceiling and comes down 17" ish. That means the semi-mount fixture would hang almost as low as the end of that wall, and I'm afraid it will look too crowded. So I think the flush-mount is the way to go. I really do like the semi-flush one, but this area is adjacent to the foyer, which is going to have two very large chandeliers, and I don't want it to be so completely busy with multiple conflicting hanging fixtures that compete with each other! Thanks everyone, I really appreciate all the help.

I think the lights below from Tech Lighting are pretty cool and modern looking. The glass is described as "gives the impression of flowing water frozen in time. The unique and elegant look of the piece changes at every angle based on how light hits the surface of the glass". I don't know what size light you need. The square one is 9 inchrs and the round one is 11 inches. You can get them in an antique bronze, chrome or satin nickel finish. They are available in three lamp configurations: incandescent, fluorescent, and LED.

I've also noticed that light kits and replacement globes for ceiling fans are harder to find locally. You could try the websites for hardware/home stores as they often have a greater variety than is stocked in their stores. They may also allow shipping to a local store where you can pick up the item. That is a good way to ensure you get the item and it is in good condition. Otherwise, you might have to buy from an online store. In general these have the greatest selection. Use their filters to limit the style, color, etc. Here are three: #1; #2; #3

Normally it's length + width of room for diameter of light fixture. Since your ceilings are only 8ft, no additional inches required.