London -> Dubai, United Arab Emirates
Number one destination for Souk shopping, race horse trading and general opulent overload.
Dubai has the world's top hotel in the Burg el Arab, whose underwater restaraunt, reachable by submarine, allows you to 'dine with the fish' as it were.
With the astromical prices, you're going to need to save on your flights; to help, I've found these 2 returns to Dubai £251 each.
Send a postcard.

London -> Rio de Janeiro, Brazil
Ronnie Biggs' hideway and mecca for Brazilian culture rush.
"The hills are adorned with favela's" sung Maria Von Trapp in the sound of music.
Rio does have the largest stadium in the world, in the Maracana, some of the trendiest drinking holes in Ipenema or Copacabana, and some of the best beaches a walk or bus ride away.
Come away with many stories to tell your friends, helicopter trip the Sugar Loaf mountain, Christ the Redeemer; kick back and generally live it up like you're a gangster.

Manchester -> Sydney, Australia
Sydney rocks. It's simply one of the best cities in the world and there is something there for absolutely everyone. Beach-lovers can jump on the ferry to Watsons Bay or Manly, where the real surfers hang out, or head to Bondi to mingle with British and Irish backpackers, who curiously coexist alongside the Sydney media types living here.
Mosey on over to some of the more bohemian suburbs such as Paddington, Glebe, and Balmain, all of which have great weekend markets. And foodies can try one of the world's very best restaurants - Tetsuya's, which has a price tag of around $250 a head. Yummy.