I'm now one disc into season three in my re-watch, and it's not as if I've never noticed this before, and the episode is still hilarious, but the fundamental flaw of "Reservations for 12, Plus Ursula" - that the Ursula situation exists in the first place because of the kids' presence, yet nothing about that makes sense - bugs me:
First, Charlene tells her parents Mary Jo and J.D. are bringing their kids, except Claudia, who is on a ski trip. So that should be four kids - Mary Jo's Quint, and J.D.'s Rex, Hannah, and Burt. Add Reese's two grandkids, and there should be six kids. Except there are five, all little (and none of them being the actors who previously played Quint, Hannah, and Burt, there's just some random, barely-seen group of five children). The live-in au pair for a long weekend makes even less sense if there are teenagers to help keep an eye on the little ones, so I understand Rex not being there from a storytelling standpoint, but they should have thrown in a line explaining his absence like Claudia's.
Fundamentally, why in all hell do SEVEN adults, four of whom are parents, need an au pair to stay with them for a long weekend to help take care of five kids? Five is how many Mary Jo and J.D. have between them, and just the two of them didn't need to hire help when they went to a local hotel for the weekend. But add five more adults, to what is planned as a family vacation, and suddenly they need another set of eyes and hands?
When Reese blows off the objections to the old lady they'd just interviewed, he says all she has to do is sit there if they want to go to a movie, and J.D. says when the kids are at the beach at least one of them will be with them*. And that scenario - hiring a babysitter to watch the kids one evening while the adults go out - makes sense. Having an au pair board with them does not.
*But, of course, as the guys are headed to the beach with the kids, Ursula shows up, so they not only decide to sit in on the interview, they send the kids on ahead alone!
With that said, the episode is hilarious. Delta Burke's line delivery when Suzanne tells Mary Jo, "I mean, here you have this gorgeous girl who gets up at 5:30, cooks your boyfriend's breakfast, then goes jogging with him. And what do you do? You're in the bathroom trying her brassiere on your head!" is perfection. As is Charlene's initial, "Mary Jo! You put her bra on your head?!" reaction. And, of course, Mary Jo's compulsion in the first place. "Suzanne's fits me like a beanie, but Ursula's covered my whole face."
I also love when Julia smacks Reese on the butt when he tries to roll over and go back to sleep.
And other than the parenting/grandparenting fail, the characterization is right on -- Suzanne is the only one who takes on Ursula herself; the others aren't annoyed with her, they're annoyed with how the guys react to her, including right in front of them.