I'm going to wait till after vacation to break up with my fiancee
Why do you want to wait until after vacation to break up?
I prefer not to cause drama before vacation.
I get wanting to save your vacation from drama, but if you know you want to break up you shouldn't wait. Your fiancee will feel horrible once they find out you were leading them on to salvage the vacation.
My vacation is very important to me.
I'm sure your vacation is very important to you, but so are other's feelings. You should not be leading someone on just because you want to relax and have fun.