barca

hey guys first time poster long time reader

me and 3 of my buddies are planning a Eurotrip this April/may, we are planning on staying in hostels the whole trip, with the exception of a night or two in a hotel

we are planning on visiting the following destinations:

-Greece (iios and santorini, 3 days each)
-Rome 3 days
-Amsterdam 4 days
-London 3 days
-Barca 4 days
-Ibiza 3 days

were wondering how much a trip like this would cost approx., what cities are more less expensive, whether its cheaper to fly, ferry or take the train, what hostels are the best in theses cities and thei