While they have been talked about loads it has to be the UK lost wooden coasters for me. I think they all would still be great fits for each park below.
Alton towers cross valley coaster
John Wardleys Cross valley coaster would have been amazing, if it were to be an Intamin Pre-Fab and have that 200ft drop I think it would have easily been the best coaster in the UK. Using the valley is the only way Alton could really get a Hyper style coaster (unless they dig a massive hole), I hope (while very unlikely) it could be used for something one day.
Thorpe woodie
While I would have preferred anything to Saw for the most part, this one hurts as it looks like a great coaster, with the track weaving over itself, a station fly-through, loggers tunnel fly-through, airtime and loads of twists & turns, this would have been great for Thorpe, I think it would have worked great with the IP to if they kept the theme.
Paultons wood coaster - GravityGroup?
So it was just a mention in a Q&A with the park but before Tornado Springs a Western area was thought of, and a woodie was the centre piece, I think I remember hearing that some of the Paulton's team went to Grona Lund a long ago so something like Twister might have been, I love Tornado Springs and Storm Chaser is a great addition but an air popping little woodie would have been my choice.