Letters of Rec for Low GPA, poor student. Forum

[snapdragon]

So I'm getting ready to ask for my academic LORs. I've got 2 very solid professional people (and could get at least 1 more) ready to write, but conventional wisdom seems to be that at least one letter of rec from a professor is a must.

I'm four years out of undergrad, and had a 3.1 GPA. I have 3 professors I am thinking of asking, all from my major. I think these professors liked me and found me generally intelligent, but the problem is, I was kind of a screw up during college. My attendance was poor in certain classes, and some assignments were turned in late. I'd love to ask a professor that I constantly performed well for, but I was really thoughtful and screwed up in at least one class with most of the professors that I had. Spirit of sharing and all. So, based on the below, who should I ask and how should I address the fact that I've taken the last few years to become a more responsible and focused human?

1. My adviser, Prof X: A young professor in the English department who was on sabbatical at least 1 year of our relationship. Got an A- in one class with her, B- in the other (one of the aforementioned screw up classes). She was very sweet, and I think that she liked me, but was disappointed in me. Not sure I made a huge impression on her, honestly.

2. Prof Y: Took 3 courses from Prof Y - B-, A-, Pass. The A- and Pass were both in my senior year, when I was somewhat less of a screw up than the previous years. Prof Y is from my hometown, very intelligent and sharp, and probably the person that I should have asked to be my adviser. We got along well and I think she would remember me - definitely did a good job with class participation and presentations in her class. The B- is not so terrible from her in comparison with other profs, she is a hard grader.

3. Prof Q: Took 2 courses from Prof Q, A, A-. One my junior year abroad was a small course, and I know I was a "favorite". The second course was my senior seminar, which I produced a lot of writing for and got an A- in. Both courses were small, and I definitely did well with class participation. Out of all the professors, she probably saw my screw up side the least.

I'm leaning towards asking both Prof Q and Prof Y and hoping that one or both says yes. What is TLS' opinion on this and do you have any advice or suggestions on how to approach these professors (via email unfortunately) to humbly ask for an LOR despite my less than stellar academic history?

Thanks much!