When it rains, it pours...eh pig! Congrats on the interviews. I have first hand experience with one, and friends that have done the other, so here goes.
EK's process is a long one, that tries to get an overall picture of you, the person, as well as your leadership qualities and decision making abilities. There is not much focus on your technical knowledge, however it is probably wise to do some brushing up on things like Theory of Flight. The Sim is pretty straight forward, and again, is looking more at your mental focus and decision making, over your flying ability. If you do some research of previous posts on this site, you will see that the majority will advise you to just be yourself. I think that this is sound advice, as you will be caught out if you put on an act.
The feedback I've gotten on the Etihad process, is as follows. Fairly lengthy and detailed technical interview, mostly on the Airbus. The guys I've spoken to, have all left that part of the process feeling totally dejected, because the questions require almost an engineer's knowledge of the aircraft. If they are happy with you, you are invite to have a go at the Sim. From all accounts, it is pretty straight forward, but totally hand flown, with no flight guidance. Go figure. Anyhow, that's about it. They also let you know quite quickly whether or not you were successful.
I will not advise you one way or the other, but would advise that you take some time to stay a couple of extra days in both Dubai and Abu Dhabi to check out the important things, such as price/availability of schools, price of groceries, and general cost of living, and most importantly, whether your family will like it in either place. Remember, the airline will only be a small part of your existence here.
Make a holiday of it, enjoy the process, and best of luck to you. Hope this helps. V.