Bring the largest sheets you can find. The king beds here seem to vary from barely fitting my sheets to being impossibly big for the king sheets.

Bring favorite kids toys. Toys here are rubbish and pricey.
Bring a good supply of books-until you get hooked up with TLG which has a wonderful book table, you will pay a lot for reading material.

Bring good pots and pans. You can find them somewhere here, but by the time you figure out where, you will have already purchased awful ones in desperation. Plus, they will be very expensive here when you do find good ones.

Most kitchen things you will find, but not all will be up to your standards. If you use a good food processor, bring it(and the proper electric gadgets to make it work properly). A good kitchen aid mixer, too. Both things can be purchased with the proper electric cords online-or for a lot of money here. There is a store, Tavola, in a few places here with really good stuff for kitchens-again, it is a question of figuring out where it all is when you need it the most.

If you can bring/ship favorite food tidbits, might be a good idea. Its hard to find some family favorites, though after a while, you can find anything but pork products or vanilla extract here. (I'd bring vanilla extract, but that's just me).

Bring your patience. Nothing here works according to your "rhyme or reason". It takes awhile to get used to Doha's rhymes and reasons:)

Oh, and whatever you buy, remember to hold on to receipt and be aware of return policy. It is kind of horrid here, so beware. This country does not have an easy return policy.