We highly recommend the Lion tours of the Cotswolds, from Bath. Paul was our guide. He is flexible and able to respond to people's needs; for a small extra fee he will drop you/your luggage somewhere near your next stop if you don't want to go back to Bath. The day we took the tour, there were horse trials which were causing traffic jams, so Paul took an alternate route from his usual Cotswold tour, in order to avoid wasting our time in traffic. We appreciated this! He took us down some very scenic back roads, the kind that big buses would not go down, and he changed the itinerary of towns slightly, yet still gave us a very satisfactory Cotswold tour. He was able to be spontaneous -- he led us down a country path that wasn't normally on the tour, because the Upper-Lower Slaughter path was too wet that day. Paul was talkative & full of information about the places we visited.
The Mad Max tour was good also, although it was our guide Mike's first time in a new van and the people in the back often had trouble hearing, as Mike was new to the equipment and could not get the microphone working right. The Mad Max tour (we did the all-day tour) included listening to a CD by Mad (Madeline? I meant to ask) herself while driving from place to place. With this tour, you arrive at Stonehenge before the crowds (get right on the shuttle bus to the stones & do the museum afterwards). The new visitor center gives you an audio guide which makes the experience more meaningful than it was last time I went; as you walk around the stones on the path, you listen to your audio guide explaining things. Avebury (less touristy stone circle ruins) is fun because you get to walk amongst the stones & sheep. On the all-day tour you also visit 2 Cotswold villages, Castle Combe (War Horse was filmed there) & Lacock (parts of Harry Potter filmed there). Mike gave us good guided walks around these villages. We also saw the chalk horse (photo stop) and Silbury hill. I enjoyed the Mad Max tour and would not hesitate to recommend it, but I have to say, the Lion Tour to the Cotswolds was the best. NOTE: reserve ahead online for either Mad Max or Lion Tours! these tours fill up! The nice thing is that (in both cases) it's a small van (only about 12-14 people per tour) but since the van is small, it will fill up.