I've just climbed the massive spiral staircase to the fifth floor café (there's a cute cheering soundtrack at the top), after seeing the first floor and basement. The 'remix' exhibit of contemporary aboriginal artists was cool, as were the model ships in the basement. The most affecting image I've seen so far was the Slaughter of the Innocents, a beautifully rendered painting of babies being dashed on marble columns and women being put to the sword. Ugh.
I'm now refuelling before tackling three more floors of contemporary, Canadian and African art. The AGO rules. Sorry VAG, but your collections don't hold a candle. But you do have a nicer patio and café. ;D