Spider-Man Loves Mary Jane (and, you know, the other series that come before it) suffers from a pretty common issue that movies have when they're dealing with high school--a desire to just do too many "traditional high school things" that don't actually make sense with the timeline they've established. I've estimated that Peter is around 15 to 16, maybe a sophomore, based on some clues that make sense, and some clues that don't.
Things that lead me to believe Peter, MJ, and the rest of the regular characters are probably around sophomore year:
First, for those of you not familiar with the US school system, a sophomore in high school is in tenth grade; they usually start as 15 to 16.
1. Flash Thompson remarks that he can't wait to get his permit; in New York, you have to be 16 to get your learner's permit.
2. None of the cast are particularly concerned about college yet.
3. MJ refers to eighth grade being "a billion years ago," but Flash thinks it's recent enough to still be valid as evidence MJ wants him.
4. In Ultimate continuity, Peter Parker becomes Spider-Man when he's 15; assuming Peter's birthday is in the middle of the school year, that makes pretty good sense for the flashback we see to when Uncle Ben died "a year ago," which is also apparently the first time MJ became aware of Spider-Man.
5. MJ is getting her first job in the MJ miniseries, which would fit in pretty well with that timeline.
So I think...throwaway comments make that make the most sense, and knowledge of the timeline. But god does the not-sense-making piss me off.
ISSUES WITH THIS:
1. The Homecoming Queen race. Having attended several homecomings and other dances, well. The idea that the contest for Homecoming Queen would be between two sophomores is ridiculous. (As a side note, BtVS actually got this right, and I was very proud of them.)
2. Ditto Flash being the quarterback.
3. Ditto MJ being the lead in the play.
4. Classes, um. MJ is taking algebra, which everyone I have ever met covered in, like, eighth and ninth grades.
5. Furthermore she's taking algebra at the same time she's taking physics, which we had in eleventh grade and at the same time as calculus. Maybe that's just my school. But still.
6. We see various people who seem like they could be younger than MJ and crew, but no one who looks older.
...I feel like there were more. MOSTLY there's this really stupid thing (that I know builds drama and blah blah blah BUT what's going to happen NEXT YEAR WITH ALL THESE BIG ISSUES also Liz's total investment in Homecoming makes almost no sense if she just has another chance next year) with the cast members having to be the most important people omg. And...it really makes sense in a limited sense, from my perspective--MJ and her friends being the most popular people in their grade and basically ruling that scene is perfectly reasonable, but the importance they have to the school as a whole rings really false to me, and makes my head hurt a lot. Which...isn't actually important.
So, in conclusion! I feel pretty confident that I have to be right about them being sophomores, it just angers me that they're sophomores. Because I am a bitter, twisted shell of a human being.