Dave,
We'll be a day behind you - flying out on the 20th June. We always used to go in May or October when it was quieter and a bit cooler but we've gone at this time for the last 2 years. We were expecting the worst but found that you can still get a lot done as long as you're prepared to hit the parks at opening time and make full use of Fastpass or Universal Express. Once you reach about mid-day/early afternoon everywhere will be busy but by that time you will have crammed in a lot. Then you can take some time out, go back to the pool or whatever, and go back into the parks later in the afternoon/early evening when the crowds will start to thin out a bit.
This worked for us everywhere. An hour after Magic Kingdom opened one morning last July we went onto Splash Mountain with only a 5 minute wait, went back round to the queue and were back on again within 10 minutes. By about 1 o'clock the queue was about 90 minutes long.
We followed a similar strategy for the water parks. If you're there for opening time and don't waste any time getting lockers or towels, you'll have about 90 minutes to do as many slides as you like before the queues start to build up - except for Downhill Double Dipper at Blizzard Beach. The slow loading time on that one leads to an early build-up so we usually do that a couple of times as soon as the park opens then move onto the other slides.
As long as you plan your day a bit, you'll have a great time.
Gerry
