As a ohotographer, I need all the capacity I can get which means a backpack and laptop bag for carryons (they can fit under the seat or in the overheads of most aircraft, including CRJ and Saab 340). I check a rolling duffle with clothes, tripod, etc.

Biggest gripe (in addition to lethargic airport baggage manglers): Bin Hogs who routinely carry aboard oversize bags. I know what the size requirements are as I can't afford to check my gear (even planeside valet is verboten).