Meyrick Park immediately springs to mind. A restoration back to the old Colt/Dunn course could be amazing.
http://www.golfclubatlas.com/forum/index.php/topic,13751.0.htmlI'd like to see Coxmoor get spruced up abit too, it looks abit tired and has done for a few years now and there are some really poorly placed trees out there, but it is a solid routing on some really good land.
Being selfish I'd love to be let loose on my old home course which is the course I grew upon, Radcliffe-on-Trent. It is nothing to write home about and never going to be brilliant but it could be a far better course than it is now. The course has suffered from some poor planting and greens committee/greenkeeping decisions over the years. I would guess there a dozens of courses like this, pretty average but could be far better with a bit of help.