To guarantee space in your favorite hotel or home, it is best to not wait to long. Tourism has started to pick back up, so if your needs are specific, its a good time to do your shopping. If you are just a couple winging it, then not so much. Anyway, when finding something on Expedia/travelocity, etc. it is always best to contact the hotel direct for availability, as they only allow so much inventory to those sites. Any always ask for them to meet or beat the rate you see there......they can and will do this when asked! Regarding slides, as mentioned Si Como No has a great one in their pool, though no TVs in rooms, so that can be a deal breaker with kids. Your family might also enjoy Arenas del Mar, or if on a budget maybe Byblos or Costa Verde. Otherwise, Tulemar is a great family friendly property with many options that may work perfect for you. Enjoy!