I have always said that to improve your photography, visit an art museum!
If you are a landscape photographer, you have a special reason to visit the San Diego Museum of Art. Kindred Spirits: Asher B. Durand and the American Landscape will be on display until April 27, 2008. I visited last weekend-- it's well worth it!

Kindred Spirits, Asher Durand, 1849
What can a landscape photographer learn from Asher Durand? Plenty! Durand was a founding member of the Hudson River School, a group of artists whose idealized, Romantic, but realistic portrayals of nature still resonate today. Aside from the considerable enjoyment gained by looking at the pictures, a photographer can take away plenty of pearls.
Durand's use of light is exceptional. Most of his works are painted in mixed light, sunshine mixed with clouds. Many photographers are disappointed when it's not a cloudless, sunny day. Study Durand's work, how he uses the play of light on the landscape, how he leads the eye with his use of light and shadow. Be humbled!
If there ever was a painter who could paint trees better than Durand, I'm not aware of it. It is remarkable. Photographers should study his work to see just how a forest can be rendered.
Durand was after my own photographic heart with his use of the color red! In many of his landscapes, he deliberately included a small detail of bright red, to catch the viewers eye. It could be a piece of clothing on a settler or an Indian, or even a tiny head of a woodpecker in the forest!
Study his portrait of Andrew Jackson to see mastery of light in a portrait.
The San Diego Museum of Art is one of my refuges that I head to when I need inspiration. This exhibit, along with its companion: Plein Air Past and Present, is one that you can return to many times for inspiration, and, if needed, instruction.