June shouldn't be too busy. I've been late May/ early June before and queues at Universal / Busch / Seaworld were fairly minimal (other than the really big attractions). Disney is busy whenever you go.
Ultimate ticket seems to be the way to go. Previously, I've always hunted for separate deals, but couldn't find anything notably cheaper than the UT for my trip this June.
Other than that, there is loads of good Florida info in the thread below this one, so have a dig through that