It seems you need to clarify your intentions or at least what you have expressed is not clear to me. I understand you are not interested in travel but you want the low cost and low maintenance of RV living and you want to be able to visit the daughters and son in Boise and Fresno. What does it mean "to be able to summer in Idaho and winter in California"? Where specifically do you plan to spend that time and what are you going to do? Those decisions could seriously impact the RV choice and your costs.
At 81 you also need to think ahead and plan for ageing and developing health issues.