Sam's Club or Safeway?

I would like to have a temporary job at either of these places as a cashier, a few months after graduating High School. I would probably be working there for 2-3 years while I am getting my Associate's Degree from college. Which of these two would offer a higher salary from the start? About how much money would I make per hour? Which is most likely to employ a first-time worker? Would anyone happen to know roughly how many hours I would work per week? Thanks, in advance.