We are thinking about visiting Croatia in early November, so my question is, is there enough to see and do in Croatia to last 5 days sans the beaches?
Croatia is a huge country--there is plenty to do and see!
If you visit just Istria (peninsula in Northern Adriatic region of Croatia), you could explore it for 7 days.
If you visit island of Hvar (opposite of Split), there are at least 10 small towns and villages, plus UNSECO listed 'Stari Grad Plain' to explore, will take you 2-3 days.
Plitvice lakes are National Park where you can easily spend 2 days.
Zagreb, capital of Croatia. 2 days there and perfect base to visit castles in NW of Croatia, Plesivica Wine Region (45 minutes drive from Zagreb)...
Sure, you can find interesting stuff to do in Croatia in 5 days