karebear,
Will you be spending the entire day at the resort? If so, then I'd definitely recommend the main building concierge if you can afford it. It's perfect if you are arriving early and planning on relaxing there all day. Depending on the time of year and occupancy, you can let your concierge pre-planner know that you will be arriving early and they will make a note for the room assignor. You'll be met either at your car or in the lobby by a concierge greeter and taken upstairs for a private check-in. If you're room isn't ready, there is a beautiful, spacious lounge to relax in and get a cool drink or something to eat. They have offerings throughout the day and end it in the evening with delicious desserts and liquers. It's a great spot to sit and listen to the orchestra play. You can request a castle view room (not guaranteed), but if you do get one, you can grab a glass of wine from the concierge lounge, take it back to your room and enjoy the fireworks from your balcony.
If you are not planning on being around the resort much or really want to experience the beauty of the GF, then I'd go with the garden view. As a previous poster mentioned, Conch Key is great for this and it's a nice quiet building.
If you want to explore, there is path that connects the GF to they Poly that is very nice to walk on. You can also go to the boat dock and take a ride on the resort launch. It travels around the lagoon to the Poly, the MK and back to the GF.
The GF Cafe is a great spot for any meal. It's casual and we always ask for Izzy too. Gasparilla's Grill is their 24 hour counter service and the food is pretty good here also.
HTH,
Tammi