I just can't believe how unimaginative the suggestions above are. What's the point of going all the way to Bali and staying in a resort that could be anywhere in the world? And the Aman in Ubud is old and definately not worth the money.
The most magical hotel in Bali, in my opinion, is the Begawan Giri. This is a hotel like very few others, and in a truly unqiue setting. Take a look - you will remember your honeymoon!
http://begawan-giri.com/
regards
Riaz