For what it's worth a few opinions from our trip the 11th to 18th
Housing: We rented a house because we had the in-laws along as well as my wife's aunt and her 12 year old cousin who cam over from the Tampa area. Rented this place
http://www.villasatkissimmee.com/rentalsearch/villahouse-kissimmee-wi-fi-356 and it was great. I know staying on properties is convenient but if we had gotten 3 rooms it would have cost more plus the wife and i would have had our kids in our room and no privacy. If it had been just the 4 of us we likely would have stayed at the parks but traveling with the extended family I highly recommend the house. Only annoyance was the pool door alarm that my father in law tripped about 5 times when people were sleeping. Great location for the parks we did, 15 minutes to Sea World and 20 to Universal, and that is time until you are parked.
Flights: Flew Allegiant into Orlando/Sanford, yes it added an extra 30 minutes drive to and from the airport down there then Orlando International but I saved more then that time with only a 30 minute drive to Allentown on my end instead of an hour plus with traffic of having to fly out of Philly. In addition the security lines in Allentown are 10 minutes when busy versus Philly which is always a delay.Flights down and home were both right on time.
Parks: We did the Universal/Sea World 14 day pass (they don't do a 7 day) since we had done Disney 3 years ago. We had never been to either Universal park so it was all new to us. My older son (11) loves roller coasters so he was thrilled, my younger son (8) is afraid of heights so he sticks to the lower rides but still found plenty to go on. J gave the Hulk a big thumbs up at Islands of Adventure, said Harry Potter was ok and was in love with the Manta coaster at SeaWorld. He was in line to ride Rock It (next group to get on) when they closed it for weather in the area. My personal favorites (not a coaster fan) were Transformers 3D and Bluto's Barge, needed that cool down with the heat. We also really enjoyed Men in Black, it was a little dated but being interactive was cool. Jurassic Park was fun but I thought they could have done a little more with it. My biggest disappointment was the Minion ride, with the movie just out I expected more given it was the longest wait in the park. The shows in Universal (Sinbad Stunt Show and the Movie Animal show) were ok but nothing great, the shows at Hollywood Studios were much better. The Harry Potter area was cool just from the way they had it done and you almost felt like you were there. I will say on Sunday night just my wife and I went and around 8pm you could have walked onto any ride in 5 minutes.
SeaWorld we had actually been to just last year when we stayed an extra day after my wife's grand mothers funeral. I love Sea World, I enjoy the shows and just the way the park is laid out. We got to see Shamu this time as we just happened to hit one of the two weeks the show goes dark last time and we also got to do the Empire of the Penguins ride which was closed last time we went. As I said my older son thought the Manta was the best coaster he has been on. It's also a more relaxed day which is nice after a few days of hustle bustle at the other parks.
Shows: Went to see Blue Man group at City Walk, awesome show. I would highly recommend it. Really cool for adults as well as kids. My 8 year old who is never really excitable with a show of any sort was on his feet clapping and dancing just caught up in it. It's interactive and fun.
Beach: Went over to Cocoa Beach one day because my wife has a good friend that lives over there. Can't say enough about the beach there. If you are use to the Mid Atlantic Maryland and OBX beaches it's totally different no steep drop off so you can go 50 yards out and be waste deep, water is much warmer, great free public parking, parks and bath house plus of course the big Ron Jon surf shop. Had a great dinner on the water in Port Canaveral.
Karting: If you are into racing at all check out the Orlando Kart Center
http://orlandokartcenter.com/ the place is a blast. This isn't your boardwalk karting so if that is what you want then go somewhere else. They have a 5 foot minimum height and I wouldn't recommend it for kids unless they have some experience driving something (ATV's. dirt bikes, etc.), my son races karts so he had a blast beating the adults he ran against. We were over 40 mph through the speed trap and when you are 2 inches off the ground it seems even faster.
Overall: Fun trip, parks weren't too crowded for the most part although we did get in the middle of some large Brazilian teenage groups a few times that got a bit overbearing. We'll probably do Disney again in 3 or years when the kids are like 14 and 11 with just us and stay on site. They'll be old enough then to do some stuff on the resorts by themselves. I don't see how some people do this as their big trip every year. Next year is either California, Bahamas or OBX for us.