We stayed at Orange Lake for 2 days in a two bedroom (recently renovated) West Village golf villa and 1 week at Sheraton Vistana Resort -- 2 bedroom (recently renovated) in the Cascades section -- this past June. You can pay for activities at Orange Lakes al a carte (the lazy river is still $9/day/person) or $49/person for a 7-day stay that includes all the activities. There are definitely more things to do for 8-12 year-olds at Orange Lakes than at Vistana Resort, if you plan to spend any days at the resort. There are more restaurant opportunities at Orange Lake and nearby versus Vistana Resort. Both resorts have a variety of pools to choose from. At the end of the trip, my wife preferred Orange Lakes because of the variety of activities for kids; I preferred the more up-scale feel of the Vistana Resort.
For Orange Lake, I would recommend joining the Holiday Inn Priority Club (free sign-up) and for Sheraton Vistana Resort, joining the Starwood Preferred Group (free sign-up). At Orange Lake we signed-up for the 45-minute tour (that took 2.5 hours), but as a Priority Club member we received four complimentary $49 activity passes for the whole week as our "reward" for enduring the presentation (it was worth it just for the two days we used them). There is also a special line for Priority Club members that could save you about a 45-minute wait at check-in. At check-in for the Vistana Resort, we were assigned a room next to highway 535; when I asked for a different room assignment, they noticed I was a SPG member, and I received a building directly across the street from the main rec center, and was asked, "What floor would you like?"
If you plan to stay in a 1 bedroom unit, Vistana Resort is definitely the better choice, as the Orange Lakes 1 bedrooms in the high rise buildings apparently are still in much need of renovation (except for River Island).
Avoid the East Village at Orange Lake; it is just across the highway from the water treatment plant.
