I really haven't read any of the splatbooks, just culled off the web some random things like feats. I have a few campaign books that I happily use, but I have some strict limits on how PCs get access to the prestige classes/feats/spells in them.
Mostly this is campaign flavor, not me trying to be mean. I've tossed paladins for a range of knightly prestige classes, banned monks because I just can't like them, modified rangers, etc... because I am trying for a particular type campaign.
In the game at the local shop I'm going to be running soon, the game is core only and will stay core only. This is because it's an "open play" game with "first six at the table" being the ones who get to play (regular players get first dibs on spots after a couple of weeks to prove they're regular and absent/late regular players will get return dibs over new arrivals). If I let "anything go" I already know I'd have one Drow clone nut and one "I gotta play a not-evil hexblade" guy insisting on their particular fetishes. If I say "core only", there's a hope they'll behave...or just not play.