Sounds like you will have a lot of time! That is great!
We had an adorable cottage: www.rentcotswoldcottage.com
We enjoyed going to Blenheim Palace as well Sudeley Castle in addition to all the little villages. We enjoy Chipping Campden and wish we had more time there (we just went to for dinner at a very old pub). It was very beautiful. So many great places.
We did Broadway, Bourton-on-the-Water, didn't walk too much in the Slaughters because it was windy and not great weather. Saw the Swells, Stow -on-the-Wold, Hook Norton, Great Tew, many others.
I really enjoyed Snowshill, it was one of my favorites. It is just a tiny little village of houses and a church and pub. It was really special. Also, go to the Lavender fields nearby. Do you watch Downton Abby? You probably can not get tickets to Highclere Castle if you haven't already bought them. But, we loved going to Bampton!! It is their major film site outside of Highclere. We had only watched a few episodes when we left for England, but since we have come back we now see that almost all street scenes, church scenes are all filmed right there in Bampton. And, we were the only people walking around the village.
We really loved the area, and really enjoyed staying in a cottage in a little village with a pub on one end and a church on the other. Diving distances are pretty short and somehow we managed to not have any crowds.
Nigel has great information and helped us, as he grew up in the area.
Have a great time!