Hi,
You have a terrific plan that will enable you to "taste" a bit of the different regions in Israel. There are many wonderful accommodations in various kibbutzim. These range from the more basic guest house up to luxurious hotels. A good place to start your search is: http://goisrael.com/Tourism_Eng/Items/Accommodations.htm. Here you will find an overview of accommodations available in Israel and several useful links both to kibbutz accomodations as well as regional links. The search function on this page is also very useful in locating accomodations - both geographically and by type of location.
You can check out the Kibbutz Hotels chain at http://www.kibbutz.co.il/en_lodging.cfm - which lists their options geographically.
You can find anything you want in Israel and I'm sure you will find lodging that meets your needs.
We're waiting to see you this summer.