Not sure about the most pines, specifically, but the Adirondacks has the largest contiguous forested area in the US. It's also worth noting that the tree density in that forest is much higher now than it was a century or two ago, due to well-meaning but misguided fire-suppression policies. The same is true in many Western forests, as well.
Oh god, I sound like such an aspie!
As for a prettier place ... that's entirely subjective, of course, but there are some magnificent mountains and forests in the Rocky Mountain states, particularly Montana, Idaho, Arizona, New Mexico.
This is near Flagstaff, Arizona ...
