Pencil Sketches for Tower Defense Concept

So I'm an avid iphone game player. I download and play a LOT of games... and mostly i dig the tower defense games. But every time I play one I think to myself, its missing this feature, or it'd be awesome if you could do this, etc. These are some concepts I've come up with for a td game, I have a great idea for it too, but I dont have enough time to get you excited about it, so I'll post it later. Enjoy some imagery =)