I wouldn't stress too much over a daypack. Just stay away from "Dollar Store" packs and get something heavy duty.

I'll offer you take a look at Jansport daypacks. They're nearly indestructible, guaranteed for life, and they've got a lot of models to choose from. I've got two and after about 7 years of pretty solid use they are still in great shape.

_________________________
--

"You want to go where?"