I agree with most on this site that the old-school traditional links style courses are a blast to play and often provide the most diversity of golf shots, which makes it understandable that many of the newer "I gotta play that" courses being built recently (i.e. Ballyneal, Sand Hills, Chambers Bay) follow that trend.
However, as much as I feel there are many courses that have become overran by flavor-of-the-month-greens-committee tree plantings, there are still some gems that exist out there that are naturally forested and a blast to play.
What's your favorite?
Personally, I know Augusta has quite the forest, but still seems pretty open in regards to what I'm looking for....my favorite to play that comes immediately to mind is Poppy Hills. The cypress forest is both unique and beautiful and plays an integral part of that course's strategy.