My overall experience with Eithad was good, (food, service). They only thing is that your carry-on weight can't be more than 12 kilos, they will weight it at the gate, they did that at Dallas(Sept 2015). Abu Dhabi airport is good, free wi-fi another plus point is that it has public showers. The other good thing is that the US Immigration and Customs is at the airport, so on the way back you clear US customs there, before getting on the plane. About sleeping at the airport, you can call Eithad's 800 and request for a sleeping pod. The airport also has a hotel inside the airport, look at the airport website for info.