We've stayed at all 3 as well. I agree that you can't go wrong, but International Drive (tuscany) is my recommendation. (Although, we are taking a 3 day visit this month and opted to stay at Parc Soleil).
- Parc Soleil: Newest resort, has only 2 buildings (of about 8 planned) which are both adjacent to the pool/amenities. Has more of a hotel feel with interior hallways and more floors (something like 12 stories per building). The pool is very nice and is toddler friendly since it has a huge zero entry area (gradual slope). That being said, the back pool at International Drive is quieter and even more kid friendly in my opinion (and has the same type of zero entry). At PS, the outdoor cafe seating is also right at the sloped pool entry, which makes it a little less family-friendly for just relaxing and watching the little kids. The views from the room aren't exactly my cup of tea - either you have a view of the barren property outside the HGVC, or you are stacked and racked above the pool with a rooftop (of the lobby) around the second floor level. Rooms are nice, but no carpet (could be a pro or con depending on your kid(s)). My kids loved the bathtub which filled from a nozzle in the ceiling.
- International Drive: Has the nicest grounds in my opinion. Nothing fancy, but it is a relaxing environment where you can take a nice stroll around the lake in the evening, grill at one of the outdoor gas grills (PS only has charcoal pits, not very convenient in my opinion), or walk to the pool(s) or playground. Rooms are nice. Would request a room with a lake view. Buildings 1 and 2 are very close (on top of, almost) the main pool/lobby. We prefer building 4 (or 3 or 5 for that matter, but we've always gotten 4 when we ask for it) since they are closer to the back pool. Any building isn't far from anywhere, but relatively speaking that's the layout. If you like to use the patio for dinner, avoid a room which faces the back of the property (west) due to sun. (the easiest way is to ask for a room facing the lake or towards Vineland Ave (east). Also, if you really want to get picky, and if it suits your needs, some of the 2BR units have one of the BR's with 2 double beds (as compared to most units which have 2 BR's with 2 Queens). Could be good for the MIL/kids(s).
- Seaworld: Has been 5 years since my only stay there. The pool was very nice. Didn't have zero entry, but it has a shallow kiddie pool which was nice. The room was definitely bigger than comparable rooms at either of the other two, but it was also not quite as nicely appointed. Could just be my memory casting shadows, but I personally rate it behind the other 2.
Location: If you have a car (and you will need a car), then the locations are all roughly equal. They are each less than 5 minutes away from each other and all have easy/quick access to main attractions and roads. For Disney, Seaworld would be the most distant, but only by a few minutes.
