I've learned not to go to Walmart after church on Sunday! Everyone in the county is there! I think weekday mornings or afternoons are probably the best time to go for easy check-out.
I'm with everyone else on self check-out......they're nice if you only have a few items, no weighing, and no coupons. Otherwise, it's probably faster to go to an actual cashier.
** This is a really random fact, but in one of my college classes were talking about self check-outs.....did you know that just one of those machines is over $25,000! I would say a store has to take in a lot of money to justify that!! :)