Do not recommend supervisor positions unless you're making a career out of it.
Pros
Started out as p/t cashier, promoted to COS 9 months later. Advancement/movement opportunities are good, even within your own club. This was a 2nd job for me, and they were pretty good about working around my scheduling needs. Pretty run of the mill cashier position. Big focus on Plus upgrades, but if you formulate a good spiel and genuinely try hard, you'll do fine. I'd say pay was above average for a similar position elsewhere in the same area. Most of the associates in my club (and even some of the managers) were pretty cool to work with.
Cons
The day I became a COS was the day I started to hate my job there; I literally feared going to work. Management will ride you to no end about sales, particularly Plus. Now, I was always pretty good about my own Plus numbers, but I detested having to be responsible for everyone else's as well. Additionally, I had always had a very good rapport with my fellow cashiers when I was one of them, but when I became their boss and had to be the bad guy about Plus, several of them started to hate me. Running a busy front-end can be extremely frustrating; it gets very trying on a Saturday to have to deal with lines 10 deep, 3 cashiers wanting (needing) breaks all at the same time because they're approaching lockout, floor partners being uncooperative and making excuses just because they don't want to help run register, getting glared at and swore at by members while prescanning because there aren't more lines open, having to cover breaks for the door people and cart pushers, on top of being asked by management every 20 minutes what the Plus numbers are. This may just be what some people thrive on. Not me; I was in the process of transferring to a different position (even back to cashier) when I accepted a more lucrative job offer elsewhere.