There's plenty of good resort style hotels in Nusa Dua in Bali, the ones you've listed are amongst the best in the area (along with the Grand Hyatt). Keep in mind that Nusa Dua doesn't give so much of the flavour of being in Bali, being a somewhat separated enclave. It's easy enough to head out for sightseeing tours though and then being able to relax and unwind later back in the resort.

With only four nights I'm not sure if I'd recommend splitting the trip between destinations - with a couple of extra nights it would be easier to do half down by the beach at Nusa Dua (or Jimbaran Bay as well, for the InterContinental, Four Seasons or Ritz Carlton as options - I'm a fan of the InterContinental personally, especially the Club Rooms ^ ). Then the other half could be done in the Ubud area to soak up the culture of Bali (and the shopping's certainly cheaper up there as well ).