re: Croatia - Hvar, Korcula, or both

At least two nights in Hvar. It is easily accessible by ferry to/from Split and Dubrovnik. Most people start in Dubrovnik, ferry to Korcula, ferry to Hvar, and then ferry to Split (or the reverse route). Korcula is worth the stop, but IMO not as much to do as in Hvar. Instead of Korcula you could stop on Vis, which was just rated as having the top beach in Europe. Split is good for two nights, with easy day trips to Trogir, Krka Nat'l Park, or Sibenik.

Sretan put!