flat CRT's tend to strain your eyes less than regular CRT's because they help reduce glare. some flat-screens look distorted for a while because you're used to looking at something curved, and some flat-screens actually do have distorsion. as with any moniter, I'd make sure you look at one before you buy it.
I think that generally you don't have an immediate choice between two moniters of the same specifications except that one is flatscreen and one is not, because flat screens are generally present on higher end moniters.
from personal experience, I've been quite pleased with switching from a curved CRT to a flat CRT, though it is quite a bit heavier...
as far as your question, "does the big ones work as well as teh lcd's with only appearance differences?" CRT's (the big oens) are very different from lcd's. lcd's generally have better geometry (you don't have to fiddle with the controls for hours like you do with crt's), but are limited in their choices of resolutions.
Also, lcd's will almost always have some dead pixels. additionally, many LCD's will exhibit ghost trails during games (and during DVD playback I've also heard).
crt's are cheaper and generally all-around more likely to satisfy your needs in a moniter, but they are much larger and produce lots of heat.
hope that helps-