No personal experience, but everything that I have ever read on this subject suggests that you really need a 12 gauge slug to bring down a grizzly in a self defense situation. IIRC there were reported cases of grizzly being killed by a 357 mag, but those were the hottest loads you can ever find (probably self loaded too) shot out of a 6+ inch barrel with a sniper scope into the most vulnerable body part. And those were professional bear hunters, which means that THEY were choosing when to shoot, and they had plenty of time to take a good aim. Self defense situation, on the other hand, is totally different. (Your normal 9mm, 357, 40S&W and 45ACP won't even always incapacitate a well determined human attacker.)
Since a shot gun is not really practical in your case, I would go with the most powerful hand gun round I can find. (Hand gun rounds that were designed to fire at humans won't do much in a bear country IMO)
I would recommend one of the Ruger revolvers with a short barrel ("short" means quick to draw, and easy to point in very tight spaces ex: when a bear has already brought the human down, the human can still point a short barrel at the bear, even during the fight.)
Something like this:
http://www.ruger.com/products/superRedhawkAlaskan/models.htmlAs was mentioned before in this thread, 44 mag will also take a cheaper 44 special
Edit: That being said, if you just want to make a nice addition to your collection that is easy and cheap to shoot, and can be practically used for self defense (in a human world), get some Glock, SIG or HK in 9mm