To be honest, there won't be any 1080p broadcasts for some time yet. The only things that will use 1080p are high end games consoles (PS3 and IIRC also Xbox360) If you don't play games on consoles, 1080p is no more than futureproofing at the moment, and if you're going for a 32" or less I doubt the difference will be earth shattering even if/when 1080p broadcasts do come along. As for 100Hz, I've not really seen it in action. I don't like the principle - in order to reduce motion blur, when 50 frames per second are broadcast, the TV goes through comparing adjacent frames and generates a "halfway house" frame between each frame and the next. Thus frames are displayed alternately - half of the time it is displaying broadcast signals and the other half it spends displaying images it has made up. I would need to see it in action to be convinced any algorithm used to interpolate the data from the broadcast frames could generate anything useful for these extra frames. But it's supposed to be the way to go if you watch a lot of footy and motor racing.
My advice is get either a 1080p 100hz one to last you about 5-7 years Or get a really cheap 720p TV to tide you over But as previously mentioned its only useful for games consoles, Blu-ray/HD-DVD players, SKY HD, and the imminent Freesat HD
I have a 100Hz CRT and the only thing I can notice is that it makes a complete hash of horizontally scrolling titles. Don't know whether an LCD screen would share this problem.