Houseguests

I've had a string of houseguests for the last two months. Some were relatives, some were friends. Some were a joy to have and hardly any work at all. Others were, hmmm how to say this nicely, a drain to me and my husband and it was work to "entertain" them all the time.
Let me skip to two recent guests, I'll call them A & B. Both are very old friends, both are fairly close. A asks if they can do anything before they do it and then washes the dishes right after they make anything. B does nothing until we ask if they want something and then gets waited on. B will "hang out with us" in the living room until we go to bed. A will go to bed at their usual bed time or even sense that we're tired and just go. B doesn't say "please" or "thank you", apparently thinking that the initial "thank you for letting me stay here" does it for several days. A says "please", "would you mind if", and "thank you" for almost everything they do. It almost gets annoying but it is nice that they notice the extra lengths that we are going to for them. Both are familiar, but I enjoy A's familiarity and I feel taken advantage of with B. While I can't do anything right now it brings up questions for me to answer. What kind of guest am I? Do I come across needy, haughty, ungrateful and inappropriately familiar? Or do I enjoy the benefits of familiarity while expressing gratefulness in both word and deed? Is there an inbetween or is A the perfect houseguest? Some of it is definitely personality and I don't think I can completely copy A's manner of making themselves at home and still communicating gratefulness all the time. But B just drives me crazy. By the second night I almost couldn't speak to them because I was so tired (of their company, from my day, of entertaining...) I'd like to put a few questions out there, maybe someone else has a suggestion or maybe I'll discover the answer.
1) what is too familiar?
2) how often should one express gratitude?
3) can I tell a guest that they have worn out their welcome?
4) is it okay to do dishes at someone else's house?
5) what am I teaching my kids, or what WILL I teach my kids?
6) do I have to confront B & tell them (next time) why I don't want to host them? Or can I get away with a "it just doesn't work for us right now" cop out?
Just venting and working it all out as usual....