ok - let's go back to the OP. We have rides in the southeast, and we have a ride in Wales, a ride to the east of the Pennines, and a ride to the west of the Pennines.
If there's a gap it's further north, and, possibly, the Midlands.
I can't get a Scottish ride up and running for 2012, although I'd like to do one if somebody organises it. Edinburgh to Dundee looks good for 2013. Going over the top from Carlisle to Newcastle has 'possibilities' for 2013.
As for the Midlands - Peterborough to Cleethorpes or Skegness (Cleethorpes has the better rail service) would patch a hole in the map, as would Nottingham to Skegness. I'd love to do a Birmingham ride, but I've not been able to work one out.