I don't live in Las Vegas but I do have know people who fly out of McCarran pretty frequently and like to utilize the Sleep and Fly service at the nearby Best Western. This is the property:
https://www.bestwestern.com/en_US/book/hotels-in-las-vegas/best-western-mccarran-inn/propertyCode.29058.htmlThey have an airport shuttle — which is quite rare in Las Vegas — and free breakfast. Be warned that, depending on which direction the wind is blowing, you can be right in the flight path of planes taking off or landing; they provide ear plugs. If you can handle that, I'd recommend it, and you should go ahead and stop reading here.
You may
or may not shave a few bucks off of that by staying at the Excalibur, which is the cheapest casino hotel on the end of the Strip near the airport. It's old and funky and smells like smoke in the common areas (non-smoking rooms are readily available), and I recommend using an OTA like
booking.com (with which I have no affiliation) which will make really explicit what all the hidden fees are. Absolutely nothing is free (including internet! and parking if your friends stay one minute over an hour), and airport transportation is not included. Lyft is by far simplest way to get there but the Westcliff Airport Express bus is only $2 and will take you right there from the airport (to Excalibur that is; it doesn't serve most of the Strip), though frequencies are not good.
https://www.rtcsnv.com/wp-content/uploads/routes/wax.pdf I know people who have stayed at the Excalibur and suffered no ill effects, but comparing prices is going to take a few minutes of research since casino prices are so opaque.
There are lots more options if you were going to rent a car anyway but I feel like that should be enough to get you started if you aren't.