I carried a 17" MBP to class and it was heavy. It was a bit unwieldy when I had to run to catch the train. Otherwise, I liked having my computer with me.
On the other hand, my friend hated taking her 17" MBP and eventually toted her husband's white MB to class instead.
My friend and I are under 5'5".
If you haven't already, go to the apple store and look at the footprint of the various Mac notebooks. If you're able to, you should try and pick them up as well, so you get a feel for the weight.