...except for Friday Brunches from 11:00 to 3:00.
Your best bet would be the Ramada, where there's always a buffet going on, with lunch overlapping breakfast. One grade lower than the top 5 star hotels, however considered "affordable", specially with kids.
I think most of the usual brunch locations are at hotels and they only do it on Fridays. Perhaps Al Shaheen at Sheraton does it. Give them a call.
Or try one of the many eateries on Salwa road.
Also check The One at the Landmark mall (yes, the furniture store).