Thank you all.
I got the Deutsche Bahn link from another post here on the forum. Thank you for pointing me to the UK Rail site.
Regarding the Bath question, we aren't oppposed to Bath, it just isn't a chosen destination for us. The reason we are thinking of staying there is to rest after the flight, have access to renting a car, and being near Wells/Glastonbury.
I know I'll get grief for this, but we have pretty much decided to rent the car and do Wells, Glastonbury and Stonehenge in a loop, staying that night in Salisbury. I know, I know...everyone advised against one night stays and long driving days. But we are from Seattle where it is perfectly normal to have to drive many miles in a day. We have mapped it out, adding a lot of cushion to the approximate drive times, and we feel we are okay with it. We aren't really big on visitor center/tours, we prefer to see the location for ourselves, for as long or short as we choose, then move on. So we won't be spending 2 hours at Stonehenge, we will park, take the shuttle, and gaze in wonder. Then we'll head to Salisbury.
In the morning, after we visit Salisbury Cathedral, we will drive to Lacock (yes, it is still a destination we are quite interested in) then on to Stow-in-the-Wold for 2 nights.
It seems there is a big difference of opinions on the forum regarding driving vs trains. Our original thought was driving on to Conwy, and on to the Lake District before going to Edinburgh. But RS has a suggested itinerary for those not wanting to drive, and it seems it is quite doable to take the train to Wales, then take the train/bus to the Lake District, followed by train to Edinburgh. I don't want my poor husband to spend his entire vacation driving in an unfamiliar area, so unless there really are great reasons to keep the car (which I am open to hearing and considering) I believe the trains will work for us.
I hope this is coming across as complaining, I'm not! I truly appreciate your comments and suggestions, but it is rather head spinning when half the room says drive, don't take the train, and the other half says don't spend all your time driving, take a train.