Well, would you look at that, a Little Women theme! I thought for a second when I put in the name LOUISAMAYALCOTT (39A: Author who created the characters named by the starts of 17-, 24-, 49-, and 61-Across) about whether or not I had put in anything else literary yet, but I was trying to go quickly, so I didn't figure out the theme until I had finished it up. After consulting with Frannie, I can report that they are not presented in order of age (Meg, Jo, Beth, Amy), but hey, you can't have everything all the time. Just ask Beth. … What? Too soon?
I enjoyed the puzzle just fine as it went along. I like the word SCALENE (47A: Having sides of different lengths, as a triangle), and being reminded of old-timers GAVIN (44A: Actor MacLeod of old TV) and 55A: Three-time A.L. batting champion Tony (OLIVA) was ok with me, plus - I always like seeing ORONO (15A: Maine university town) in the grid, because my Dad went there.
I've never heard of "poppers," but AMYLNITRITE (61D: Chemical compound in "poppers") was filled in entirely by crosses, so it didn't much matter.
I liked the Latin clue, 23A: "____, vidi, vici" (VENI), because, hey!, remember when I said I was sad because I hadn't signed up to read the Aeneid? Well, I signed up after all! And it's going great, thanks!
Lastly, once I put in BYEBYELOVE (11D: 1957 Everly Brothers hit with the repeated lyric "Hello loneliness"), it became the SOUNDTRACK to my solve, and there's nothing wrong with that.