What is it you shoot most? $3k can get you a lot of very cool kit if you think about it and have a good pro shop nearby. That sort of money should get you some serious discount. Look at second hand stuff too, you could get a MKII used very inexpensively these days and there is not a lot to go wrong with them, even the shutters can be replaced for not too much. 5DII is very cool, but if you want to shoot sports you may be better looking elsewhere. 8 1/2 frames a second is a real eye opener, as is the AF. However for more contemplative work and a lighter load a 5 series does rock. Do you want Primes or Zooms? Primes are easy, at least in the canon line up, 50 1.8 is terrific for the money (although I use a 1.4) the 85 1.8 has that certain something, the 100 f2 is excellent too and all not too pricy. The 35 2 is slow and noisy but very very good as well. The L series of primes ive never had, but I do want them. Nothing beats the 70-200 2.8 IS, the 17-40 is quite sexy too (Ive not had the 16-35II yet) and most L zooms are very good. The 24 - 70 2.8 just seems to me to be getting a bit aged, or at least mine is.
To me its always been the glass ive invested in, the cameras seem to change a lot but my shooting style has been defined by my lenses in many ways.