I'm a big fan of the LL Bean rolling backpacks - not the most "professional" looking luggage out there, perhaps, but extremely sturdy and well-designed - there's a lot of pockets, and a lot of room.

I had a High Sierra rolling backpack which broke the first time we used it - to their credit they acknowledged a design flaw, and sent an improved version for free. I have yet to use it, but the handle still looks a lot less sturdy than the LL Bean bags.