Everything that I read above is correct. I just want to add a few thoughts/experiences of my own:
1) REFUSE TO SIGN UNTIL THE AMOUNT IS THE SAME AS YOUR PAID RESERVATION: I use Payless every time I go to Las Vegas and know what to look for. Yes, they will insist on mandatory roadside assistance. Be polite but firm that you refuse to pay for it. As an aside, I once had my Payless car break down the first day and the emergency roadside number told me to call the airport location directly. I left messages all day and not one call was returned. I drove the car in 110 degree weather to the return and most likely damaged the engine, but that was not my fault.
2) MAKE SURE THEY DONT INCLUDE THE 'OPTIONAL REFUELING CHARGE": There was a woman at the counter who told me the amount was higher than my reservation because they include the optional refueling charge but that it would be deducted if I return the car filled. DO NOT FALL FOR IT. I refused and she removed it.,
3) DONT FALL FOR THE UPGRADES 'DEALS': I am a big man: 6'4" and 250 lbs. The clerk commented that I reserved a compact car and suggested that such a big man should upgrade because they had a special. She then actually claimed that a larger car has stronger air conditioning and would be worth it because it was 110 degrees outside. I said "no thank you." She kept offering me upgrades until I told her to get her boss. She then told me that she was going to just give me the upgrade for free.
I thought my charm worked, until I realized they were out of compact cars and had to give me a free upgrade to a Toyota Tacoma. I have to admit that it was really quite clever to try to make me pay for something they would be forced to give me for free.
4) BABY, IT'S DARK IN THERE: One thing that all of the car rental companies have in common at the Rental Center is the lack of lighting. It is dark on purpose to hide damage to the cars. Use the lights on your phone to really inspect the entire car BEFORE you accept it. Mark damage on the forms and take photos BEFORE you leave. You will be tired from the flights, excited to get to the hotel and casinos, hungry or ready to rest a little. Take the few minutes to check things completely INSIDE AND OUT (I once had a car that was really filthy in the back seat).
I was talking to/flirting with a couple pretty Midwestern women who were in Las Vegas "to work for the weekend." I knew what they meant and still admired their looks and honesty. When they got into their car, I suggested that they inspect it for damage and I explained why. They let me use my phone light and they saw that someone keyed the length of the car on both sides near the ground. I also showed them that the roof (only in Vegas) has curse words scratched into it. They got another car and offered me a nice time if I want to hang out. I politely declined but enjoy the memory of what might have been.
