I think we can all relate to how stressful the resort booking process can be. I went back and forth many times but ultimately decided on the Del Mar. A few reasons:
1. I LOVE the open air venue. Del Mar brides have first choice of that venue and it was very important to us. I've heard mixed reviews if Lindo brides can book the Del Mar restaurant. I think it depends if it's available on your day.
2. The rooms are much less expensive for our guests at the Del Mar. We want to encourage as many friends/family as possible to join, so we went with this option. If some people want a nicer resort - they can upgrade to the Lindo and we have rates secured for them. At the end of the day, knowing our group of friends we'll spend all our time at the pool having fun - so a nicer room isn't as important for us. In regards to being able to have unlimited "a la carte restaurants" (the other difference with Del Mar) - we have people coming in every night of the week and predict we'll just go with a big group to the buffet or try to get extra reservations when we're there.
3. The only two wedding ceremony options are the gazebo and beach. I originally wanted to gazebo because it's more private - but it's fairly small and we're predicting a larger wedding guest group. We'll probably end up at the beach - but my sister's fiance is in charge or moving ALL swimsuit beach goers away from the site so they aren't in pictures (i keep having nightmares about an old man in a speedo in the background of every picture).
4. there is a separate wedding planner for each resort. once you book they've been very quick to respond (surprising for Mexico)
Overall i don't think you can go wrong with any of the Iberostar resorts. For us it came down to our own budget and trying to be mindful of our guests. We know we can have fun anywhere so why spend the extra money for the grand.