Personally for me, my resort pick is going to change many many times I am guessing, unless the Barcelo has everything I want and the price is ideal, etc. We originally wanted to get married at a Riu, nothing else.. then we became a little more open and we were leaning toward Dreams, and then we were looking at other resorts like the paradisus, etc. And now we're on the Barcelo, which isn't set in stone, it could change any time. So if you're like me, you'll be sending out many websites to your guests with new resorts or new prices. I think as long as the guests know the time of year you're planning on going and an estimate of cost, they'll be able to save up until next year when you're able to book for sure and tell them this is the ONE! It's not going to change! (well... we hope). And they can book and everything too. I wouldn't worry too much about your guests. Maybe give them a list of your top 3-5 resorts or something and they can go online and look at the resorts, which will make them excited too. And then once you narrow it down you can tell them which one it'll be.
It's exciting to research resorts and look at peoples pictures who have had weddings there before, and really decide which one you LOVE!!! I used to want to decide the resort right away, and I would say, "that's the one!" and then when I saw something I didn't like about it, I'd get dissapointed because I got my hopes up. My mom was the one who actually talked to me and said, "What's the rush? You should be enjoying this part and pick the one you know is going to be perfect. Take your time"
Although I still want to book really bad!!! haha.