We spent a week there at half-term. Thats me, the wife & 2 kids aged 9 & 13.
We spent most days on the main beach, which is gorgeous, with soft fine sand and clear warm sea. The sea is very calm and very safe.
Towards one end of the main beach is a set-up where you can go on various inflatables towed by a speed-boat.
One day we went out on a boat trip, which was very enjoyable, where there were plenty of stops for swimming etc.
There is an aquapark near by, which you can get to by using a tour operator, or do as we did by catching the dolmus. The park was surprisingly quiet for half-term, which was good as we never had to queue to go down a slide. There are various slides & pools, including a wave pool, and we spent all day there.
There are many bars/restaurants, particularly on the front, and we ate out every night and never had a bad meal.
There is a large market in the town, which is held on saturday, which is good for local produce or cheap clothing/shoes/gifts etc.
Hope this helps.

Thanks for the info Biddulphian, sounds like just what we need

i have been going to altinkum for 10 years now, my 2 dughters were 3 and 9 when they started going and they loved it. There is a lot for you to do as a family crazy golf, boat trips which are brill, the water parks which is great. The place is quite flat and everything is close at hand. We have stayed in a few hotel/apartments and have no complaint about any. The local people are great with kids and have watched my 3 year old grow up to a teenager and my 9 year old grow up to be an adult they never forget the kids. You should really enjoy it there.

Thanks very much for your advice shazney64 resort sounds ideal as I will be taking my mum with us also and the idea of the resort being fairly flat appeals to me more now.