For 12 nights I would do amanusa either at the beginning, if late flight, or end if early flight. Although I like the property I think 3 nights is adequate. I would Allila Ulluwatu second for 4 nights, ( have been to Legian years ago so sure it is improved, but notnon my list althoughncould be sub),and lastly Amankila in the indrkilasuite suite for 5 nights. I have been back to that room, cannot resist!
Sounds wonderful!