Hi, welcome!
I looked at the Riu as well, but they have a requirement that a certain percentage of your guests has stay at their hotel, something like 80%. I'm planning on having around 50 guests, and I want my guests to have a choice in where they stay, so that was a deal-breaker for me. If you're having a smaller wedding, that may not be an issue for you. The travel agent who is helping me also said that the Riu's have had some problems with their beaches eroding. She recommended the Lindo to me.
Good luck!