I'm always on the lookout for restaurants that are child friendly, especially ones with play areas. Here's a (short) list of the ones I have visited so far. Please feel free to add any places you know.
Piatto's (Exit 5)-great play area upstairs and good kids menu. A great restaurant but has been super busy every time I've been.
Outback Steak House (Localizer mall) -indoor play area
Applebees (King Abdullah Road, Al Hamra) small indoor play area
Chilli's (Tahilia street) outdoor play area
I've heard that TGI Fridays (King Abdullah Road) and Applebees on Tahilia street also have play areas but I haven't visited them.
Hope this bit of info was helpful to someone.