I wouldn't visit any cities.
Over priced and full of tourists.
Road trip on the bike with a tent and meet the real people, starting in Spain and doing a circuit of the Mediterranean. I especially want to visit Iran on the way round.
Sydney - visit mates and rellies, eat ridiculously good food, body surfing.
Melbourne - visit mates and eat ridiculously good food.
Amsterdam - weed, cheese, fine art and techno.
Berlin - mates and beer.
Krabi (well, Railay Beach - close enough) rock climbing, tropical beaches, weed and king prawn Lak Sa.
Paris, Morocco (in general) , Barcelona, London and Goa. ?
The only culture in London is generally responsive to penicillin....