Bonsour,
I have stayed at the Plaza several times. I would not hesatate to stay there again. The rooms while not fancy like some on the strip. Are nice, clean, confortable, and of a decent size. I prefer the North tower myself. Because of location of the elevators. But, the South tower rooms are pretty much the same as the North tower.
As for Reno, if you want to walk from casino to casino. Plan on staying somewhere downtown. I am not to famillier with the casinos downtown, as far as rooms there. I usually stayed at the Boomtown Casino in Verdie(10 to 15 miles outside of Reno). So I will not offer any suggestions here. Except for downtown, the casino's in Reno are pretty much spread out.
I might suggest you think about renting a car for a day or 2. Then you can catch the casino's that are not downtown. And make a trip up to Lake Tahoe(beautiful)and catch the casino's up there. Lake Tahoe is about a 1 hour drive from Reno. This is a place I always try to go when I go to Reno.
Have a fun and safe trip.
Dan