Welcome! I always knew I wanted a DW and didn't even have to convince FI since he was the one who first brought it up when we got engaged! My family was all for it as well which really helped. For us the hardest part was choosing a location. We first considered Maui but found that because there are no all inclusive the price would have been a lot more money for everyone. Then we considered Mexico. We looked at possibly every resort in the Mayan Riviera and just couldn't find one that felt right that were still decently priced for family and friends. Also, to get legally married in Mexico it can take alot of work and money! We then thought of Punta Cana, but once again found the legal requirements to be quite confusing and whatnot! We then decided on Jamaica as getting legally married is pretty simple (no blood tests and document translation) and we fell in love with a resort with a beautiful gazebo on the ocean! Not to mention we got a price that everyone was happy with. We did consult our Travel Agent and she was the one to give us some great resorts to think about and compare, and then we did a lot of research on each resort. I have never been to the Key West but I'm sure its beautiful. I guess you just need to determine if all inclusive is important to you and your potential guests. Also, a nice think about Key West is that people could choose to only come for a few days verse a week at a resort, which might be a nice option for some guests and would help keep costs down.
Good luck deciding! And happy planning:)