I should mention that the other art assets are from Scirra's graphic pack. They are just being used as place holders right now.
I am leaning towards Tree 3 right now. I am going to spruce it up a bit and then update the game on the arcade. See how it looks in action.
EDIT: This is what I came up with. Off to bed, leave comments.
<img src="http://img90.imageshack.us/img90/2391/t4y.png" border="0">
and in-case you have images disabled
Tree 003