2 days beyond bologna

You might get more helpful responses if you say what sorts of things you're interested in. Also, is this your first time to Italy? Venice would be the logical choice. Padova would be a good but unexpected choice.

I lied. it is for my daughter that I pose this question--2 18 year olds. they have been to venice when they were younger. what about ravenna?

Ravenna is a great half day sight. I might suggest Ferrara , which I enjoyed more than I expected, as a base for seeing Ravenna, but for two 18 year-olds I would think the Dolomites, or possibly Innsbruck, a better choice.

Ravenna, San Marino, Ferrara, Vicenza, Padova, Verona...all within an hour and a half from Bologna (driving).

If they want to meet other 18 year olds, it would be hard to beat Padova. It's loaded with college students. It's also right on the train line between Bologna and Vienna.

Padova is a university town, assuming that school is in session when your kids show up. It is nothing like OU or even PSU. Padova U is totally urban, there are no leafy quads. I am sure that there are hangout cafes, but they will have to be ferreted out. But, assuming that Padova U were something like OU, just picture two 18 year old girls wandering around the frat houses at OU, not speaking the language. Not sure that's a good idea. Anyway your kids have resources far beyond this Board: they have Facebook, so they will find ways to get connected - in fact they probably already have. Looking back at it decades later, when I was 18, the coolest place that I possibly could have imagined would have been Venice. Your kids have never have seen anything like it because there is nothing like it.