The hotels that I have stayed in in Downtown (and I find both of them to be fine) are Plaza and Four Queens.
I think that the rooms are decent in both and they are not far away from the casino action as well as Fremont Street.
If you like having the noise from Fremont Street, then at Four Queens, request a room in the North Tower. They even have rooms where the windows face the Fremont Street Experience under the dome.
RecVPPlayer