My dogs are 9.75, 9.5, and 7.75. Molly had her three year rabies this year, and I won't do it again at 12 if she is still with me. Fletcher is due this year, and I will give him the three year rabies, but again, that will be the last one. I'm not sure when Sallie is due again, but she will get one more, then stop. I've stopped all the others as well. They aren't exposed, and after 10 or so, I just don't think it's necessary. (No, I don't get a flu shot for me, either )
The only thing that might change my mind if I were in your situation is the wildlife. I think you live in a fairly rural area? What are then encounters with local wildlife like? Incidents of rabies in your area?