I buy romaine hearts that come in a package of three. They seem to last for about a week. I usually use two hearts per meal when salad is served as a side dish. I think this lettuce is quite a bit more expensive than head lettuce, however, I have much less waste.
I used to buy one bunch of romaine and one bunch of green leef lettuce and I would wash it thoroughly, tear it into bite-sized pieces, discarding all the ribs (they seem to go bad faster than any other part), dry in a salad spinner and store in a large sealed tupperware bowl and use it throughout the week. I think it stayed good about 5 days if I was careful to get it really dry and keep all of the ribs out of it.
I love salad.
Here are my faves:
Greek: romaine, cukes, feta, lemon juice, olive oil, salt, pepper, oregano, granulated garlic and granulated onion. Could also add red onion, kalamata olives, tomatoes, pepperoncini, garbanzo beans
Balsamic cranberry: romaine, cucumber, red onion, dried cranberries, feta, balsamic vinegar, olive oil, granulated onion, granulated garlic, salt - would be good with spinach too.
Italian-ish: romaine, cucumber, lots and lots of parmesan cheese, red wine vinegar, olive oil, oregano, granulated onion, granulated garlic, salt
Creamy Greek: romaine, dressing made from one part mayo, one part sour cream, lemon juice to thin, chopped cukes, crumbled feta, oregano, granulated garlic, granulated onion, salt and pepper