Best tyre for 17" rims Options

[marc]

I've just got some 17" alloy wheels but need to get some tyres for them before I can put them on the car. I've done a search on the forums but it doesn't seem to be working

I'm running 205/55/15 at the moment, that's the standard for a GT right? Which is the best size tyre to get for

a) looks
b) to keep the rolling radius the same
c) comfort

I've read about 215/40/17 and 215/45/17 tyres but I've also read about 205/45/17's somewhere. I'm confused which is best for me.

Also, what will my Celica look like with 17" wheels but standard suspension? Will it look like it needs lowering?

Thanks to anyone who replies.