Sean
For the West Midlands I would pretty much second your 3 course choices in: Harborne, Whittington and Beau Desert. Apart from 2 or 3 dull holes around the clubhouse, I think Sandwell Park isn't far off either with several superb holes (5th the best). Copt Heath too.
I lived mostly in the South Midlands/South East and would basically just second Mark's recommendations of Berkhamsted, Moor Park (+short course Tricky Ricky), Beaconsfield, Denham, Burnham Beeches (some unusual holes here, particularly the sleepered par 3, 10th). I would add Ashridge too but it does occasionally make a Top 100. Crews Hill is a really good shorter course too. The back 9 in particular.
I've also visited Bournemouth a lot and Richard didn't mention Meyrick Park, which apart from a poor 18th, is super. The par 3s as a set aren't far off Swinley, Sunn New etc.
On the Colt trail: Tandridge, Brokenhurst, Canterbury, Manchester and Leckford are excellent. I think I'm most fond of Leckford because it's still a 9 holer and hasn't been messed with much because for a long time it was one of the purely private courses in England.
I lived in the Cotswolds/Bristol area for a few years too. And obviously Painswick was a favourite. Minchinhampton Old is in such a charming setting (Laurie Lee country), has a great pub, and the 16th amazing, but the course has quite a lot of pasture holes.
PS If I visited the W Midlands more without the kids and more time, I'd be most curious to see Atherstone for its original 9 (not sure about the new 9)...it looks a bit crazy but full of character.