The Traveler by Liubov Popova
While I'm not necessarily one to complete cubist work myself, I can definitely enjoy it. The style works perfectly for a subject like travelling. Seems like a scrapbook full of ticket stubs, notes, pictures of places visited, signs etc...
Portrait of Leila by Pierre Bonnard
Something to aim fore in portraiture. The pose and setting is classical but the graphic pattern of the chair and the paint application is modern/emotional.
The Legislative Belly by Honore Daumier
Okay so this piece wasn't at the museum but a few paintings by Honore Daumier were there and while reading his biography I learned that he was a respected caricaturist. Having completed a stint in caricature while in college I still dabble and the subject always interests me. I believe a piece like the above can be on the same plane as, say, a Degas. (Don't get offended here -I love Degas.) It just seems that there is as much to be learned from it and as much thought and skill most likely went into it.