Borobudur 21-23rd March
I will update this once home, currently camping at Starbucks in the airport.
Suffice to say, Borobudur at sunrise was a fantastic experience. We walked in the darkness with chanting all around. There was no quintessential pink sunrise but it was quiet and almost mystical with very few tourists there at that time. If you are keen for more historical info, good old Wikipedia can furnish you with that much better than I can.
Go. For me, it beat Angkor Wat hands down.