I've just got back from Bali. Stayed at Cahaya Dewata and had a look at Kupu Kupu Barong. Do think again if you are looking to stay at any of the resorts that overlooks the Ayung River. Most of them have steps to either go to your room, restaurant or the pool. At Kupu Kupu Barong they have a buggy to transfer you from one building to another. The rooms that I viewed are very nice. You can see the Ayung river even from your bed as the room is surrounded with glass windows.
Expect the rooms to look different for Cahaya Dewata. Not like their webpage unless you call them in advance to request those rooms, even so, you may not get them.
Ubud alone is a lovely place. Loved it. I am making Bali as my holiday destination, even for weekend breaks.