Everyone had great comments and mine are pretty much the same.
Don't worry about EVERYONE. First worry about you and your fi, then your parents. When we started planning we just looked at the dates that were good for us, then asked our parents if they could make it, and checked with our siblings. That's it. We didn't worry about anyone else. If there are certain people that you definately want there then check with them but you don't take everyone into consideration. And you pick a resort, if people want to stay somewhere else they still can you would just have to pay the day pass or let the guests pay them (that's up to you). Once you pick your date and resort send out a STD with a letter explaining that this the resort your staying at, it's all inclusive, prices (or estimates), and let them know they can stay there or somewhere else. If people really want to go, they will.
In the end, you and your fi have to be happy. you don't want to look back at your wedding and wish you had it somewhere else.