I have to say that Typhoon Lagoon is, hands down, the better of the two water parks. We got there during the "extra magic hour"; guests of the resort can get in an hour before the general public. That was GREAT! We managed to go down 4 water slides each in the first 40 minutes, and they were all fun. By then, I was huffing and puffing pretty good, so we floated around their "lazy river", and then went into the wave pool.
The wave pool at Typhoon Lagoon is incredible. Their wave generator makes a surfing-quality wave that is at least 8 feet high, which actually breaks as it approaches shore. A number of people actually did body surfing, quite successfully. After running the 8 footers for a while, they switch to a different wave generator that makes, basically, "moguls". It was fun and challenging. I would go back there.
After that, my son and I headed to Downtown Disney for table service lunch at Captain Jacks. This was one of the better meals we had at WDW. I wish we could have been there for dinner instead; they told us the dinner menu is quite a bit better.
We spent the rest of the afternoon at Downtown Disney. We eventually made our way up to the "West End" and spent a few hours in Disney Quest, which is basically a 5-story video arcade. My kids had a fabulous time there. I was worn out from Typhoon Lagoon, so I actually napped for a while in the cafe...
When we got back to the cabin, it was still relatively early -- about 7 PM. It was "extra magic hour" day at Epcot, which means it stays open from 9 PM to midnight for resort guests, so we decided to head down to Epcot to catch the parts we missed. This turned out to be a joke. EVERYBODY heads down to whatever park is open for the "extra magic hours", so it was significantly MORE crowded than it had been the day before. We watched the fabulous fireworks display in the middle of the Epcot lake, and we did catch a nice counter service dinner of burgers and chicken strips at the Electric Umbrella, but we couldn't get into any of the rides. We wanted to do the Test Track, but by the time the fireworks were over, the wait was already up to 50 minutes. Only a few of the rides are open during the "magic hours", although you can bet that all of the stores are open. In fact, the "magic hour" concept appears to be primarily another way to separate you from your money. We went through the Spaceship Earth exhibit (which is a good one), and then headed home in a very exciting thunderstorm.