Do you have to pay your own airfare and hotel or does the couple pay?
You pay unless they are rich.
Family and friends spend thousands of dollars to watch a haggard heterosexual mating ritual, after which they resent the bride and groom for the rest of their lives!
Guests have to give up vacation time and buy expensive tickets and hotel rooms so the couple can boast to their friends that they were married in someplace exotic. All under the guise that it's your vacation too.
I think they're really tacky unless you've consulted with your friends and family and they're all are up for it, particularly the wedding party because they already have to spend a lot of money to be in the wedding.
Weddings are a big enough commitment. Now, if they're paying for everything, then whoohoo! But that's rarely the case.