A few years ago we went to an all inclusive in Costa Rica, I've been twice (once not all inclusive) and the only thing I'll say is that if you just stay at the resort you'll be missing a lot of the benefit of the country. There is jungle, desert and beach in one place so you have so many choices. We hiked a volcano and did some scuba diving. It's a beautiful country and the people were the nicest. Try to go outside of the rainy season as well. I loved the all inclusive tho, it was so relaxing.
I went to Costa Rica in June and stayed at Rui Palace Costa Rica. They also had another Rui right next door to our resort called Rui Guanacaste and you were able to jump back and forth between the two resorts. Both resorts are all inclusive. I suggest seeing a travel agent! Ours is amazing and they are really good about getting all inclusive packages!
@Kayla I stayed at the Riu Guanacaste last year and LOVED IT. It is a family resort so there are kids around, but I didn't have any issues with kids running around being obnoxious- and I'm not a kid person. Drinks can be a tad weak, I asked them to do extra shots in my drinks and problem solved. Food was hit or miss - some was really good, some was so so. Pool and grounds were nice. The beach in that region is not as "tropical" looking. It has dark sand and isn't the Caribbean blue water some people expect. It was more of a rustic beach, but I thought it was gorgeous. Our room was a jungle view, and we watched howler monkeys playing in the trees right off our balcony every day. There is lots of wildlife on the beach - huge iguanas, and down the beach about a half mile or so is a small mom and pop restaurant called the Monkey Bar. Good food, but expensive. If you walk down there early in the morning (like 5 am) there's monkeys everywhere in the trees. It was super cool. Staff at the hotel were wonderful. We booked 3 excursions through a company called Alex on the Beach. They set up right on the beach and have a ton of excursion options. They were beyond amazing! If you do any excursions I recommend them very highly!
I totally fell in love with Costa Rica. It's an amazing country and I'm dying to go back there for our honeymoon.
We went to Costa Rica for vacation, half the week in Arenal and the other half in Guanacaste at Playa Flamingo Resort. I love Costa Rica but honestly, the all inclusive areas are nothing special. If you really want to experience the country and its natural beauty you're better off going to the east coast near Tortuguero or the rainforests/volcanoes like Arenal and Poas, which are not all inclusive. If you're dead set on all inclusive I would recommend going to a less expensive country like the DR or Jamaica.
I don't have a resort to recommend - but look at cheapcaribbean.com. They have a really good rating system for resorts and list why the resort is good, and also list some "negatives" depending on what you're looking for.