Has anyone flown out of this airport? How difficult is it to get there from the center of Venice? How much will it cost?
http://europeforvisitors.com/venice/articles/treviso_airport_bus_to_venice.htm
Pretty much what they described sums up what my experiences there were a few weeks ago.
Treviso is pretty easy - very small airport. Just flew in a few weeks ago from Prague and flew out to Vienna from there using Sky Europe. Bought a 10 euro round trip ticket at the ATVO bus counter for the ride to and from Venice's Roma Pizzale station. You can take a water bus from there to the stop nearest your hotel. We only had backpacks so we opted to walk from the station to our hotel, stopping to eat in a non touristed restaurant along the way.