Since MANY people repeatedly said you need a car for Rio, or without a car, you have to factor in at least $24/day for Uber/Lyft, I guess not many people know the existence of Google map on your phone or how easy to use it.
I had been to Rio more than 10 times since Hyatt associated with Rio, and EVERYTIME no matter to and from airport, or to and from the strip, I only use public transportation, it is easy, inexpensive, and fast. If you stay on the strip, you should be familiar with the double decker DEUCE buses already. With Google map, it basically already shows you the directions and what bus to take, download the RTC app so that you can buy and store bus pass, scan the QR code of the pass to get on the bus Everytime, download the transit app as well, as it is basically a bus tracker so that you don't need to waste time at the bus stop
Although Rio is off strip but not that far off, as it is just across the expressway I-15 on Flamingo road, going to the strip is one stop on 202 flamingo bus and you get off right outside Horseshoe. Going to Rio from strip, you catch the 202 flamingo bus outside Augustus tower at Caesars palace, also one stop 5 min ride.
Download RTC app to buy bus passes
Download transit app for bus tracking
Northbound CX bus go to Fremont st using the expressway, southbound goes to LAS T1 and T3
Eastbound bus stop the strip
You get off the bus outside Horseshoe
Westbound bus stop outside Rio
Westbound bus stop to Rio, you pick up outside Augustus tower at Caesars palace
Deuce bus from downtown across the street from El Cortez, runs along the strip to south premium outlet