I just ran across your post . . .
3 days it's not a lot for Cuba. A few years back I was thinking of combining Havana with a drive into the Pinar del Rio area staying in Casas Particulares - which are homes stays - often with dinner & breakfast available. Lots of sites to search on Google. They are safe & certainly local.
Things are changing fast so ask on the Trip Advisor>Cuba forum for up to date currency info. But best to go prepared to pay cash (Cuban CUC) & don't assume your cell will work as a GPS either, so take a paper map for the hinterlands if you do go driving. The Guia Carretera map is the best if you can find one. I may have one here somewhere if you need it, you are welcome to it. The roads aren't well marked but they are scenic & not busy away from cities.
A customer of mine was there last week on his annual cigar tour & he posted pics on FB with his new buddy - Ernesto Guevara (Che's son) who lives in Havana. If you want an intro . . .
And don't buy street cigars. They are ALL fakes!
Ian