I have stayed at both Hyatt Hua Hin and Hyatt Bali recently. In my opionion, the Hyatt Hua Hin is a much better hotel- new, friendly staff and not far from Bangkok. The Bali Hyatt has a better sea view if you can get an oceanview upper floor room. I think the Hua Hin also is more expensive (regular room rate) than Bali Hyatt. The pools is amazing in Hua Hin, where Bali has a very basic pool. I think Hua Hin is an excellent Cat 1 Hyatt.

If you have diamond status, the private pool and lounge at Hua Hin is a great treat. I had 2 nights using points and one night using hyatt rate- not much difference in treatment.