I loved that the shorter rod allowed for more accurate and compact casting on the river. It helps to avoid entanglements in trees and brush inadvertently when a lot of the river is a "tight spot." I ended up doing a lot of roll casting on the Provo which was also a lot easier in those tight spots with the more compact rod. I throw everything from heavy mouse and sculpin patterns to tiny scuds and nymphs with my 7.5 footer. Mine's a 4 weight, and it's worked great for my purposes.
I'm with crimedog though, tailor it to the fishing you will be doing most. I'd go crazy on the Provo and other smaller rivers with the 9 footer, but I'd go a bit crazy lake casting with my shorty, so go with what works best for what you'll do most. You may want to buy the rod and reel separately, you can put together a pretty sweet setup yourself for not a ton of money.