Since I have a fizik saddle, I have the medium size bag that clips into the ICS slot. In said bag I carry: 1 multitool, 1 patch kit, 1 spare tube (for when a patch aint gonna cut it), 2 CO2 "cannisters", 1 valve for CO2, 2 tire levers. This bag almost never gets opened because I so rarely flat. I just toss it in the bike gear bag on the way to a ride, clip it on to saddle for ride, then toss it back in the bag when im done. Simple. Wish there was a large ICS saddle bag tho, I would put more stuff in there, but there aint any spare room.

I carry gels, shotblocks, etc in my right jersey pocket. I have a little satchel I keep my DL, debit card, cell, and car key in my center jersey pocket. If I need a boot for a tire, I'll just use the cover for the debit card in a pinch.

Left jersey pocket is for extra clothes I shed during a ride, such as warmers, vest, etc.

Also have a frame pump I recently picked up. It really isn't for myself, its for the other sods in the club who keep getting flats all the time. CO2 is for me