Make sure you price out a full week to see if it's cheaper to just keep the car (parking is free at all strip casinos and most other places, you can just park it and leave it between your side trips).
Thanks BK, TB, and and GLG. Great tips! The One Big Expense may be pick-up in Las Vegas but drop-off in another city. Will have to research that. Trying to extend my trip so I fly out of Salt Lake City. I want to run up I-15 to see Zion National Park and Bryce, plus whatever might be on the way to SLC. Looks cheaper to fly home from SLC than LAS.