Many US companies are recommending that people with kids not come, there are no places in American/Canadians schools here. That may be a big decision factor for you. They are offering full tuition, right? Qatar is one of the least attractive countries in the GCC, that's true, but it all depends on the friends you and your family make. You won't remember the lousy landscape, just your good friends. Also, will you be working 5 or 6 days a week? That's something we Westerners don't think to ask. I'd say 6 days is more common in the Gulf. You will have a hellacious commute to Messaieed. That adds a lot to your work day.
Mandi