Bali and the Thai beaches are the obvious choices. Farther away would be Australia, where $300 a night precludes a few of the Great Barrier Reef resorts, but still allows lots of choices. Some can be hard to get to, involving small planes and then transfer to hydrofoils, but since this isn't the start of your honeymoon, it isn't an issue.

Do not even consider taking a group tour or anything involving group travel for a honeymoon.