ceili, let me suggest that you start your own thread about central Java. No doubt you've seen a number of posts about central Java, both questions being asked for planning as well as trip reports. I don't know of anyone who has stayed at a villa in central Java, though staying in a villa is very common on Bali. There have been quite a number of posts about villas in Bali.

You will need air conditioning in both locations.

I've been looking at returning to central Java. The place I've investigated staying is the Losari Coffee Plantation www.losari.info