I just realized, of course days after the fact, that at the birthday party something really fantastic happened. All my kids are old enough that I didn't have to tend to someone or constantly scan and be aware where one or the other was at all times. I didn't have to take a little person to the bathroom or monitor for the bouncing pee dance. When we left the house, for the first time, I didn't take the Badtz-Maru "diaper" bag stuffed with snacks and toys and assorted ungents and bandages. I had conversations that lasted more than a sentence or two -- uninterrupted talking and listening. I had a really fun time myself, not just because the kids did.
This is huge. I came home a little tired, but it was because I had 2 beers, not because I was on high alert for 4 hours. That is a nice feeling.