I have the new, rectangular Rubbermaid one that folks above had mentioned - it is fabulous! Don't think I've had to throw out any lettuce since I've been using it. I'm a single person but I prefer to buy the big plastic boxes of mixed lettuces because I eat salad for lunch every day. It keeps very nice and crisp for quite a while! When I bought it, I was surprised a little bit, because I thought I would wash the lettuce and then put it into the container, but that's not how it works ... you put the unwashed produce (it works for everything, not just lettuce) into the box and then wash it as you use it.
I also couldn't live without my salad spinner!