Like David I'm sort of a "kit" person. My "main" system is a 4x5 field camera. I use it for landscape, nature and some architectural photography. My secondary system is MF (6x6). I use it for close-up, nature and landscapes. My third system is 35mm and it is used primarily for macro work though I have a range of lenses and do occasionally use it for nature and landscapes also. In addition I have a Moscow 5 folder, recently acquired, that has become my "take everywhere" camera.
The 4x5 pack has the camera, 3 lenses, 5 film holders, Polaroid holder, a box of Readyloads, darkcloth, meter, loupe, several filters, spanner and misc. supplies (lens cloth, cable release, notebook, pencil, etc.) All up it weighs about 40-45 pounds.
The 2/14 pack has the camera 4 lenses, 1.4x teleconverter, 2 backs, prism finder, waist level finder, a few filters, flash and accessories (cable release, notebook, pencil, lens cloth, plastic covers in case of rain). This one also weighs in at over 40 pounds.
I use the same tripod (Bogen 3021 with 3030 head) for both systems.
The 35mm bag has 2 bodies, 4 lenses, several filters, flash and accessories (cable release, lens cloth, notebook, pencil). This one only weighs about 12 pounds!
Depending upon my intended subject for the day I pick the system that best fits. If I don't have a particular subject in mind I'm likely to take the MF gear.
Horses for courses I guess.