We were there about 7 years ago. We stayed at the Four Seasons which was wonderful. A highlight was a cooking class offered there by the head chef. There were three of us in the class - each of us had a work station and helpers to take care of a lot of the prep work, deal with the dishes etc. It lasted all morning and then we had a lovely lunch out of what we had created. The spa was fabulous as you would expect and we enjoyed a couple of days touring to the elephant camp, temples, markets. Four nights is a good amount of time - that will give you three days for sightseeing and time for some down time.