I don't think Crimea is 'semi-autonomous' in quite the same way. Gibraltar and The Falklands are protectorates (not quite the right phrase but I can't remember what the right one is) whereas I think Crimea is a federated state, more akin to say the way the regions inside Germany have some autonomy. The Spanish government definitely won't be in any hurry to recognise/validate the vote in Crimea, given their history with Catalans.
I heard some statistics over the weekend over the level of 'capital flight' out of Russia. The number sounded ludicrous, something like 80% of the capital generated each year exits the state pretty much immediately and the vast majority gets shipped to places that are British tax havens. If we actually DID decide to impose proper sanctions it would really cause a fair amount of trouble. But I wouldn't hold your breath for Cameron and Osborne to implement them though.