I used to have custom universities in Desiderata Valley and Veronaville.
The Desiderata screenshots are buried somwhere deep, but it was half a military academy and half a Liberal Arts school. It also had a big, decorative train station, because students would arrive and leave again in a (residential lot) train, a mix of Hogwarts Express and Oriental Express. I think I put more effort into that train than in the actual uni.
As a small "threshold country" Veronaville didn't have a university of its own, so the young nobles went to Takemizu Nation. I never built the campus itself, only the neighborhood most of the dorms were situated in:
https://abload.de/img/snapshot_00000028_ea73kkb5.jpg
- Blue is a public swimming pool, that served as clothes shop.
- Red are four dorms and one private residence.
- Yellow is a weird case, because although it sits on the Takemizu University map, the dorm is actually Veronvaville's little conservatory with park. I added this lot in order not to have to create another uni for those teens that didn't went to Cherryblossom Academy.
But these two cases aside I just use the premade unis. Desiderata Valley will get Simstate, I'm not sure yet if I want to use a completely empty template or one that still has the premades (but no dormies).