First to the Royal Festival Hall to see the Koestler Award 2008. Amazing art by offenders and the highlight of my day. A free exhibition highly recommended.
Then to the Hayward Gallery to see Andy Warhol which wasn't free and I only recommend if you're a huge fan of his work. If you're hoping to see screenprints of Marilyn and soup cans, they're there but some of his better stuff like the Judy Garland we stumbled across in Portugal this summer, wasn't. There was also something else going on in the Hayward but it didn't do much for me so I won't give it a plug.
Then t'Tate for Rothko at a whopping £12.50 each. A room full of big pictures that your eyes want to make sense of and your mind wants to sink into isn't done justice when said room is full of gawping tourists and crying babies.
So if you want to do just one art thing in London in the coming weeks, head to the Royal Festival Hall for the best (and free) exhibition I've seen in a long time.