beofotch: Our baby girl was 18 months old, and I'd 2nd most of what thucanhho said except about Cambi taking babies. They told us they couldn't accept anyone under 4 unless the parents stayed there with them. We actually did hang out with our baby there for about an hour when dropping our son off bc she wanted to look at their books and stuff animals and such. The staff constantly coo'ed over her and engaged her with things, so it's a decent option if you don't mind hanging out too.
The sun IS strong. I am about as pale as they come (natural blonde, Casper-skin) and I *amazingly* didn't burn, nor did my kids. But I am uber-obsessed with staying on top of sunscreen, and I actually buy European sunscreens instead of American ones bc they have some better options over there. (Side note to any fellow pale people reading: can't recommend Bioderma SPF 50 spray lotion or Heliocare supplements enough! Without this combo, I honestly don't know if someone like me would be able to visit places like CR and Hawaii and have a good time)
The best thing we brought for the baby was this swim float:
http://www.amazon.com/gp/product/B00...?ie=UTF8&psc=1. It's a bit bulky to manage once inflated, but packs really small. It was good quality and the sunshade really helped keep our baby safe from the sun (plus a rash guard). Don't plan on being able to buy any baby sundries (diapers, wipes, etc) at the hotel bc they don't have them. If you have a rental car, it might help with not having to schlep everything to CR as we did.
Overall a very kid-friendly resort, btw, so you should feel comfortable there. Even when we got poor service, everyone called our daughter "princessa" and there were young kids everywhere.