If you are really convinced that all-inclusive is the only way to go:
Clean. Royal Beach resort area was nice since we were away without kids, relaxing music and quiet. Other areas of the resort seemed like great fun for families and singles, upbeat music and activities. Accommodating and friendly staff. Good wine and drinks (as in most all-inclusives order a double). I went with my husband and we tend to eat a bit later so we didn't have the problems that larger parties had with dining reservations. Food was very good,fresh and well prepared. The Spa services were not good. Personnel was nice but didn't seem to have too much training. You MUST get coffee from the cafe. Comparable to other all-inclusives I have stayed at it was top notch.
If you're open to other options:
I found the all-inclusive experience stifling. There is so much to discover in Guanacaste that we were off property most of the days and arrived late. Excursions (yes we used the famous Eric outside the gates of the Hotel) take up at least half the day and there is SO much to see.I will most definitely return to the area with my sons soon but will choose another hotel where I have not committed my money to meals and drinks on the property.More