Re:All Star ... go for close to the Lobby, 2nd or 3rd Level to escape ground noise especially if you are poolside. Try to view the resort map and request near the front (Close to food court and more importantly, the buses)
Re: Universal/IOA ... I would not call it a trip without visiting US/IOA. I have twin nieces (7yo) who loved BOTH! MiB was a hot with the twins but we loved the other rides. Also do the Nick tour, the girls loved it and they got to take part in the games at the end! Great stuff.
At IOA, the twins loved Cat in the Hat and the flying Unicorn but werent tall enough to ride the coasters. Spiderman freaked them out at first but by our third ride, they were seasoned pros. Please heed the warning about Popeye and Dudleys ... YOU WILL GET WET! Please take neccessary precautions (Ponchos with no socks and shoes!). Also your children will love the photo op with the X-Men, Spidey and some of the baddies (Green Goblin etc) as well as Grinch, Cat, Thing 1 and Thing 2 etc.
Re:Seaworld - Coaster fans will love Kraken and Journey to Atlantis should not be missed on a hot day. Your party should really love animals to justify a trip here. The Twins loved the shows (and I personally laughed my backside off watching one of the pre-show Mimes!). It is a different animal experience than Animal Kingdom at WDW but like I said, gauge the animal interest before planning this.
Summary: US/IOA Definite yes! Although there isnt enough toddler rides (5yo and under) there is enough attractions to keep everyone occupied! Seaworld is a matter of taste. We have visited it in Orlando (twice), San Diego (twice) and Brisbance, Australia. We will probably miss during our next trip to Orlando in September (but I maybe tempted by Kraken ....). Either way, you are in the right place and amongst the right people to get all the information you need!