The four theme answers are common phrases, with two additions...double the final consonant and add -ies. The new words are then clued in punny ways.
17A: Angry rabbits in August? (hot cross bunnies). This is one that I am sure I've seen before.
25A: Hens at the greatest altitude? (highest biddies).
42A: Cat lady's mission? (keeping tabbies). This one's a little off...I think the original phrase is keeping tabs.
55A: What a Chicago ballpark bench holds? (White Sox fannies). I think I've seen this before, too. Or something very, very close.
I'm guessing this puzzle won't be a favorite among some solvers. Even for those who don't particularly like the theme, though, there's plenty of fresh fill.
1A: Language in which plurals are formed by adding -oj (Esperanto). Here's an interesting article about it. I knew the word but didn't know much about the language itself. By the way, the literal translation of the word is "one who hopes." We had hoper in the puzzle a few days ago, and it caused quite a stir.
15A: Christian Dior, e.g. (couturier). That's a word you don't often see in a puzzle. According to this article, he was "the most influential fashion designer of the late 1940s and 1950s...[who] dominated fashion after World war II with the hourglass silhouette of his voluptuous New Look."
60A: Beach cookouts (clambakes). I can only eat them when they're deepfried. When you're in Seattle, be sure to eat at Ivar's Acres of Clams. It's one of the reasons I'm anxious to visit Seattle again...that and the Space Needle.
62A: Private chat (tête-à-tête). It's such a nice word to describe what might very well look like gossip to the untrained eye.
26D: Permanently written (in ink). For some bloggers and commenters, this is the preferred way to solve the New York Times puzzle. That's what I did when I used to solve the syndicated puzzle in the paper...ink because it feels better on newsprint, purple ink because that's my favorite ink color. Now that I subscribe online, though, I print the puzzle and solve in pencil.
43D: Masthead title (editor). When you're Will Shortz, you get your name in the paper every day. When a constructor includes your title in his or her puzzle, you get double the recognition.
I just noticed the similarity, as well as the vertical positioning, of 41D: Face on a fiver (Abe) and 38D: French cleric (Abbe).
Didn't know (but probably should have) 11D: Tree rings (annuli). It didn't help that I also didn't know 21A: Hard-to-miss hoops shots (stuffs). That U could have been anything else in either of those words. Annili? Stiffs? Why not?
While I'm not a huge fan of things opulent, I do like the word...and it appears at 40D, clued as Luxuriant. I am totally opposed to the killing of animals solely for their fur, including 31D: Luxurious fur (sable). That goes way beyond opulent. For the record, pedicures are necessary and should in no way be considered opulent.
I had a nonstop day...running from 6 to 6...and I'm beat. So, it's off to bed, and I'll see you tomorrow.