Tate Liverpool's Retrospective on Rene Magritte (it runs until 16th October 2011) is a must-see exhibition and if you book your rail ticket early enough you can still do a day return from London for under £60.
There is much to see that is new including his posters, photographs, home movies, commercial art and letters. Moreover, seeing his work as a whole demonstrated at least to me the profound influence he has had on modern advertising and on on our current crop of artists. He was so much more than the man with the bowler hat.