You could try the Radisson twin Toweres or the Holiday Inn just across Kirkman from UO. You could walk from both of these and I believe both have shuttle service.
The Super Star Shuttle bus service that stops at the bus station between CityWalk and the parking garages, has a number of routes serving a bunch of hotels nearby. Each route serves a number of hotels. So you might want to check the routes while you're staying at RPR and pick a hotel that way. You can usually get a printed route schedule from the driver.
From what I've been able to gather, the bus drivers don't check whether you're a hotel guest, either coming or going to the parks, so as long as you're near a shuttle stop, you might be able to use this service.
Does anyone else have more specific info on this?