Yes, spend more time at Amanjiwo, at week would be ideal as you want a few days just to hang around the resort.
2 or 3 days at Amanusa would be wise and remember your flight does not leave till the evening and they will let you keep your room for the whole day. If you find that you had enough of Amanusa or did not like it you know they will move you over to Amankila the next night. You know by now that they are going to make you happy no matter what it takes.
Amanusa is really great. Its a resort you never have to leave and if it was your first time to Bali I might recommend one of other resorts as you get exposed to more of Bali when staying at them. Had a room with a privite pool and it was wonderful but I find knowo one uses the public areas when I'm staying at Amans and you really end up having the public pool to your self. So don't feel the need for your own pool. The beach club serves great food and there are showers and everything you need there so you can spend the whole day laying in your bale on the beach. It is a 3 min ride on a golf cart to the beach via the golf course so its easy and quick. Two restaurants plus pool side dinning and room service you won't have time to eat everywhere. The food is really good with more options then the other resorts on Bali.

Amanwana has great diving and snorkeling and is just a really remote perfect place to chill. Try it the following year when you go back to Bali, as you know you will!