One place I enjoy to return to is The National Gallery. Here are some personal favourites.
I discovered these crabs by van Gogh and aren't they great? Not very similar to the work you'd expect from van Gogh, like the painting below for example.
Monet is always Monet and I really like the painting from Gare St-Lazare in Paris.
And I fell in love with this painting, which happened to be a new loan. Just look at the fuzzy-skinned peaches and delicate flowers. Absolutely amazing!