I really like this pack:
Osprey Radial 34 Cycling Pack - REI.com
The member rebate would bring it back to ~$150.
They also make this one which has fewer pockets/dividers and as a result a larger main compartment:
Osprey Escapist 32 Pack - REI.com
it also has a better waistbelt.
The escapist would hold my high-school student son's 2 giant binders, geometry text, lunchbox, and PE gear. He rejects it because he relies on pockets/dividers. The radial would work but he doesn't need the laptop compartment and it would make the rest of his stuff get more cramped. I have a radial and I do use the laptop compartment.