The most beautiful contemporary gallery in London aptly named White Cube, the space is an artwork in itself. Its portfolio of artists and exhibition programme is top of the league, always presented as with style and grace as the space itself.
Photograph by Paul Riddle
Slightly biased as this is where I live, but Stoke Newington is great place to spend lazy saturday / sunday afternoons getting sloshed with friends. There are 10 + pubs within walking distance who all are great places for one reason or another. I'll pick out the White Hart for its huge beer garden...
The walk along the South Bank from Westminster to Tower Bridge will take you past a plethora or interesting sights and cultural hotspots. There's always something interesting going on too.