I'm downloading the Company of Heroes demo now. If I like it, I'll probably pick it up.
On a related note, I was going to buy Faces of War (sequel to the underrated Soldiers: Heroes of WW2). FOW is a similar RTS title with destructable environments. Here's a link to the demo that features two missions.
EDIT: I've been monkeying around with the CoH demo, and it's quite good, and offers a lot of content to try out. I'm not a fan of many RTS games, but I am thoroughly impressed, especially with the fantastic AI.