What is the best tropical vacation under 1000 dollars with a drinking age of 18?

I am looking to take my girlfriend on vacation someplace with a drinking age of 18. We arent huge drinkers anyway but its always nice to have a few gles of wine with dinner. Anyway, my price range is anything under $1000 for hotel and airfare. Her birthday is july 18th and was hoping to surprise her and go around that time I appreciate any input and suggestions. Thanks for reading.