So, I was reading the gamefaqs.com FAQ on The Sims 2: Nightlife and mentioned a thing or two to Stella.
And she goes from previously "nah, don't need it" to "Wow, that's in? Let's go get it. Now." o.O
She goes out shopping with Amy and brings back a CD case and asks me to install it. Ooookay.
(I'm a bit worried that gameplay will be a bit harder because of the more complex social interactions—like with Hot Date where you suddenly couldn't queue up five or six "Tell Joke"s any more, for example.)
The main problem was with installing it: after installing TS2:N, it said "you've uninstalled TS2:University; your college sims will all be moved to the bin. If you don't want that, reinstall TS2:U". WTF?
...and it turned out the message was right: no more college neighbourhoods. Fortunately I had made a backup as the game advised. Uninstalled Nightlife, restored backup, reinstalled Nightlife: still no dice. (I had also renamed the "Divide and Conquer" room divider I had downloaded from TheSims2.com, which the program had complained about.) So I reinstalled TS2:U over the existing installation, then started TS2:N (without reinstalling): worked. Who knew.
So, seems to work decently. Haven't pulled all the stops yet but may play around with various new things over the next weeks. Or might not.