what is the most important thing to consider when planning a destination wedding?
Before getting your your hopes up, clear the location, timing, and cost with your family and anyone who's attendance you see as non-negotiable.
And be ready to negotiate with your expectations. I don't actually love the logic that it should just be about what you and your future spouse want. Sure, you're the most critical attendees, and at first you'll think about all the people that are important to you, but pause for a minute and think about how important you are to them. It's not just about the physical attendance of your wedding, it's so much more for friends and family who have raised you, loved you, and want to celebrate with you. Yes, some people not being able to come may hurt your feelings, but it may really hurt them as well that they don't have the means to get there.
On that note, keep in mind are a lot of reasons someone may not be able to go far away; children, health, money, time off work... make sure your expectations are managed and people with tight schedules know at least a year in advance. And start to accept that by choosing somewhere far away, this is the first of many tradeoffs you'll have to make, and you cannot hold it against someone if they can't make the trip. There are many private reasons a vacation may not be in the cards for someone, and trust that your true friends are DYING to be by your side, but if they can't be, it's for good reason. We didn't have a bridal party because we didn't feel comfortable mandating anyone's attendance. Ironically, everyone that would be in our bridal party ended up coming, but I felt better knowing it was less of a requirement and more of a vacation on their own accord.
Long story short, don't surprise anyone close to you with your decision; if your mind is already made up and then someone raises concerns, you'll be defensive. Have a discussion, explain why it's important to you, have some data to back up why you think it will be feasible, and tell them you completely understand if they can't swing it. If you're dead set on the location and several people can't come, just make sure that their absence won't make or break your day (or your friendship). You can alwaysmeet in the middle and have a small local dinner or event near your loved ones before or after the wedding so they can be a part of it. We had a family barbecue at my in-laws house a couple months after the wedding for people who couldn't come, and it was awesome because I had something to look forward to after the comedown of my wedding.