My advice would be to check trip advisor. I trust the reviews on that site - have always had good experiences with hotels/resorts that we researched using that site. Obviously the 5-star places get the best reviews, but I've enjoyed more "economy" places as well because I can adjust my expectations based on the trip advisor reviews.
Edited to say: most people also put their age category on their trip advisor reviews. So if a bunch of 50 - 65 year olds don't think that highly of the Riu places, but the 18-24 year olds seem to love it, you can take that into account.
