In my opinion for that kind of budget there is nothing that will top Victoria House. There are some resorts on the north side of the island which are very nice, but then you won't have the option of going back and forth late at night since the vast majority of restaurants/nightclubs are in town.
All of the rooms at Victoria House are beautiful and there are some private casitas available as well. They are known for excellent service and have one of the finest restaurants on the island. Check out their website and congratulations!!