How do you suppose the two characters would get along, if they ever met each other? :)

Alex would call Marty a "slacker." ;)

Well, they definitely do take different approaches to school. Also, Marty seems to really be into rock and roll music - while Alex doesn't care so much for it.

I do think they'd get along more often than not, though.

I agree that Marty McFly and Alex P. Keaton would probably get along pretty well. I mean, Alex got along pretty well with a lot of folks on the show that weren't necessarily like him much. Alex and Marty both seem to have a propensity for looking for ways to make money. No question there for Alex, for Marty- just see "Back to the Future Part II"- "Hey Doc, I'm all for that. I just want to make a few bucks on the side." (may not be verbatim, but there you go.) Alex and Marty both mention Ronald Reagan as President too. I get the feeling they're probably on the same political sides for the most part- though Alex is obviously much more staunchly Republican.
I think both Alex and Marty have a general belief in God as well. (Alex openly talked about it in "A, My Name is Alex" (Parts 1 and 2) and Marty sure uses God's name a lot in the movies. (lol- okay, so swearing doesn't really count toward that so much, but I just get the impression that he probably would profess a general belief in God.)
And Alex would definitely tag Marty a slacker. Ha ha. And though rock may not be Alex's favorite style of music, I think he enjoys it to some degree. He certainly enjoyed Jennifer's band performing their song in "Band on the Run" (though ironically he originally had them performing "Mr. Sandman", which of course, also is heard when Marty strolls through downtown Hill Valley in 1955 in the first "Back to the Future" movie.)
Alex has also expressed an interest in classical music and jazz and I think Marty could hang with some of that. (Mainly the jazz.) I'm not sure that either of them care for the folk music Steve and Elyse are fond of, but Alex tolerates it sometimes.
And Marty is probably more athletic than Alex, with his skateboarding and all, but Alex has also been seen playing baseball and other sports throughout the series. I think I could see the Alex P. Keaton, Marty McFly and Scott Howard getting together for a game of basketball. :-)
Yeah- Alex and Marty would get along well.