cbern your wife and daughters will not be treated here as they would be in KSA. No need to cover up with black abayas. Normal clothing is fine in public. Bikinis and mixed bathing permitted. Your wife could also get a driving licence.
The girls may not have so much fun as they could have elsewhere in the Gulf - they won't be allowed to drink in bars for example until they are 21. ID is checked - thoroughly. Not so many places to go or things to do...
But there are many expat families who are quite happy here. It aint the best place in the world but there are many worse.