I just want to put in a plug for Harvest Hosts.
We have only stayed at one, but had a very nice experience. We learned about it from a lady who lives in her class A motor home, spending much of her time doing disaster work for the Red Cross. The expectation is that you will buy something from the host. We had breakfast at the espresso shop, and bought a bit of fruit, but it wasn't anything we wouldn't have purchased anyhow. I am looking forward to stopping at some wineries on 2015 trips.