Most beach hotels will be family friendly, but how about the Jumeirah Beach Hotel as you'll get unlimited access to the Wild Wadi water park (a must visit!). Atlantis is also meant to be very family friendly and has its own water park, but you are a bit cut off from the rest of Dubai out there. Alternatively, take a look at the Grosvenor House Hotel - on the face of it, it's very much a business hotel, but they also offer apartments - so more space for the kids and you will have a kitchen as well, plus free use of the beach and pools at Le Royal Meridien which is a short walk away (they also provide very regular shuttle buses throughout the day). The apartments at Oasis Beach are also fantastic, but their beach facilities are a half hour shuttle bus ride away at the Jebel Ali hotel (although they do have a pool on site and are right next to Jumeirah Beach if you just wanted to pop over)