Between Barbados, Grand Cayman, Jamaice, St Thomas and Dominican Republic. Which island is better for a nice relaxing yet fun filled night life vacation? Also, it must be safe, so I dont have to worry about getting mugged.

If you want night life, I would pick Barbados, Gap area, or Negril, Jamaica.

Of your selections I would say Grand Cayman and Barbados. Grand Cayman will be more familiar to you because (IMHO) it is more Americanized. Barbados is larger and exhibits a more British heritage.

You can get mugged anywhere, but Barbados is relatively safe and has good nightlife (or at least it did 5 years ago when I was there)good beaches and restaurants and great sightseeing

No one has ever been mugged at all on St Barts. No one will try and sell you anything, hassle you for a taxi, try and sell you drugs, or steal from you.

Go anywhere you like night or day with not the slightest thought to your personal safety.

Great night life too!

Oh, and don't believe the super expensive hype.

Eet eez also verry verry Frrench.

No has ever been mugged before in the entire history of St. Barths? Really?

I believe St. Barthelemy is as safe as it gets, but I do find it hard to believe a blanket statement like that, waring.

barbados!
def not dom rep

I would not agree that Cayman has great night life. Nice island but not great night life.

It's true!

One of the unique things about St Barts is that there is no poverty (and that blanket statement is true as well)

If you don't have a job, no one will rent you accommodation, so you are off the island!

Sorry not on your list but......... our fave St.John & Anguilla!!!!!!!!!!!!!

Of the four you mentioned I would pick Barabdos or Grand Cayman. While Grand Cayman doesn't have a big night life, it is my favorite. Safe, and no one trying to sell you anything on the beach. (we had that in Barbados - offered shell necklaces, hair braiding and drugs while relaxing on the beach - annoying)