I have one bike to train on and that I use for RR and circuit races, basically anything except crits (look 595)
Another to do crits with, Higher BB, smaller frame, lower position, much cheaper. (system six)
Then I have a fixie for commuting (KHS flite 100, again cheap)
Then I am looking at TT bikes right now because next year there are 4-5 stage races with TT that I want to do and I'm going to need one eventually anyway.