Preferably Toulouse-Lautrec at the Allentown Art Museum.
I was honestly very impressed with this museum. It's no Louvre or Tate, but for a small art museum it is very well-curated. The Lautrec exhibit info left out the spicy details of his life. There was no mention of Lautrec residing in a brothel, suffering from a genetic disease due to inbreeding or his supposed cause of death. But they couldn't clean up the art itself, so we got a nice glimpse of Parisian nightlife in a cafe chantant, the bohemian atmosphere of Montmartre in the 1880s, celebrity culture and decadence, and cabaret obsession in the Belle Epoque.
The collection was on loan from Herakleidon Museum in Athens, Greece. It didn't exactly include Lautrec's best-known illustrations (most of which are on display in Paris and Washington), but it did showcase his life-long friendship with chanteuse Jane Avril and his proclivity for Parisian cabaret scenes. A very nice touch was the fact that the works were accompanied by music, passages from French literature, photographs and other objects meant to recreate the original atmosphere of the era.
There was one treasure that made it to the Allentown Art Museum, a copy of one of his most famous posters advertising Divan Japonais, one of the many café-concerts that Lautrec used to paint in. This poster surfaced a few years ago, after being hidden from the public eye in a dusty attic for over ninety years.
There are a few other paintings that are worth admiring at the Allentown Art Museum. Philadelphia native Colin Campbell Cooper's masterpiece, Columbus Circle, New York (1909), is breathtaking just by the amount of detail in a bird's-eye view of a bustling cityscape.
Visit this Flickr gallery for more pictures of the works on display at the Allentown Art Museum.