Burlington, Vermont. University? Check. Two smaller colleges? Check. Community college? Check. Beaches? Check. Mountains? Check. Docks? Check. International airport? Check. Castle? Sort of (two 18th century forts are in driving distance, plus Wilson Castle, In Proctor, about an hour and a half away). Number of Starbucks: One. Population? Less than 40,000, which makes it smaller than the usual definition of a "small town" in MA or NY.
If that's as close an example as any one can find in real life, this trope really is pure fiction, then. Burlington is still small enough that, Extra Strength Masquerade or not, Sunnydale's murder rate would cause panic and an exodus. Burlington's airport is international only because it is so close to the Canadian border; it's really, really tiny as airports go. Counting 18th-century forts within driving distance as castles is a big reach.