The GREs are, well, a cinch. Especially since they started doing the computer-based adaptive testing - doesn't even take all day. ETS has some sample tests online - I found the hardest thing for me was remembering some of the formulae for things (I don't use the formula for volume of a cone very often, for example, and all my trig & geometry courses were years ago so deriving it on the fly took me more than a minute).

But what you might want to check is whether a representative sample of the programs you're considering actually want the GRE (my current program didn't, for example, which is a bummer - my GRE scores are much better than my undergrad GPA....)

Good luck on the goals, though!!