some friends of mine recently did the english coast to coast, aiming to do it in 11 days.  They pretty much fit your description of your group's fitness levels.  Their schedule meant an average of 17 miles a day.

It wasn't fun. One had to drop out altogether, another had to miss some stages and get in the van with the suitcases, the others did it but didn't enjoy it, there were lots of arguments about how fast to walk with the faster and slower ones feeling frustrated with each other.

So I'd really bear this in mind. It's one thing to walk 20 miles in a day but to get up and do it again, and again and again is a different matter.

Good luck though!

yes ive been thinking about the distance to travel each day and where as for the first day and maybe the second day we could handle 20 miles, it might prove too much to expect that every day. maybe dropping the target down to 15 miles is more of a realistic approach.

I do like the idea of letting the pledgers choose the challenge as it would definatly add an involvment to it as well as an aspect of the unknown right up untill the last min.

:Another coast to coast style thing you can do in Wales is go from Prestatyn to Barmouth. Easy really - just follow the hills....

In fact that's why I like this so much - it follows the geography rather than some arbitary route line. Start on the Clywdians for a warm up then the Berwyns, Hirnuants, Arrans. Dovey Hills and finally all the way along Cadair and over the estaury. Really the worst part of it is stopping when you reach Barmouth - optional I guess .

It's been in a few books but I don't know if it's picked up a name or anything. It deserves to now that the open access has sorted out the few problems.

There's a good report (as usual) of a camping trip over the back half of this route here - http://v-g.me.uk/Trips/T0859/T0859.htm but it can also be done easily enough staying in B&B's. I did it from Llangollen that way last September. I do mean to return to do it full justice sometime.