Why are there so many threads about size?
Anyways, coming from a 17" owner, it's not too big for me at all. I LOVE the extra screen real estate. When I snap pages in half or even in quarters, it's really nice to see more on each page. I do a lot of page snapping, so it works out really nicely for me. It's also all subjective whether a 17" is too big for you to carry around. I have an Incase Nylon Tech Brief messenger bag that was made for the 17", and it is perfect. It fits the 17" snuggly inside and there's plenty of room for other things such as books, notebooks, and so forth.
If you're at your desk a lot and don't want to connect to an external monitor, then the 17" is the way to go. If you're feeble and have a tough time carrying a notebook that is 1lb heavier than the 15", then I'd recommend going with the 15". Perhaps lose some weight to offset it?
The resolution is just fine. If you have eye problems, just raise the size of the text. If you have 20/20 vision (and also with glasses), then it'll be fine for you. I never understood why people were saying "The font is too tiny."
Now, would I say that the 13" is too small?... in terms of resolution. YES. The best resolution is either the 17" or the hi-res display on 15".
Maybe some people feel as though they're "coming up short" in other areas. Dunno. Alls I know is, my 17" is perfect. It isnt heavy, it isn't bulky, res is just right and everyone comments on just how amazing it is that a 17" can be so portable yet get so much battery life.
Perfect.