If you can afford it i would stay at Universal's Royal Pacific. Its the Cheapest of the three Hotels but its my second favorite one there
Regarding the Express Passes...I was at IOA and i stayed at RP and i used my express pass from the hotel with no extra charges.But this was the weekend of the Passholders event for the High in the Sky Seuss Trolley Train Ride.
ALSO another perk of the On site hotels are the boats which take you back to your hotel which is nice because ALOT of people get drunk at HHN.
I hope some of my rambling help!