I could never get too into the back catalog before BSSM, but that album is front to back classic. One Hot Minute had some nice stuff going on, but it was clearly a different band with Dave Navarro.
I really dug Californiacation and By The Way, as I felt they really captured the calming and maturation that happens as you grow up. I definitely wasn't into Stadium Arcadium, but I maybe didn't give it a fair shake.
If you haven't seen the documentary of the making of Blood Sugar, it's definitely worth a watch. There are some torrents of it out there.