When not wearing heels to the club can you wear your flip flops or whats to go?

Hey all,

I am going on the European Adventurer in August 2010

I am thinking of taking heels to wear to the Moulin Rouge and probably for the dinner in Barcelona, but other than that are they going to have any use?

I wear heels when ever I go out here (AUS) but are the places we go out to a lot more casual over there would it be acceptable to wear flip flops to the club or do we need to take a more dressy flat??

I am contemplating not taking heels at all now that I have started to pack my back I really don't know if it will be worth it.

some advice would great.

Thanks