As I've mentioned before, I do have some pretty strong opinions about not wanting Marty and Doc to be split up - so, therefore, I don't like the idea of Doc staying in the past with his family. Others have argued, though, that Doc loves the Old West so much that he would likely end up choosing to stay there permanently - and that, as long as they're careful of what they do, staying in the past shouldn't be as risky to the timeline.
While I agree that the space-time continuum in BTTF is a lot more "forgiving" of minor changes made in the past as opposed to, say, The Butterfly Effect - you do still have to take caution with the changes that one makes in the past. This kind of a lifestyle actually wouldn't be fair to have imposed on Jules and Verne - as they didn't actually choose to be born in the past. It was the actions of Doc and Clara that caused them to be born.
Anyway, I'm wondering if anyone here thinks there would be any difference between Doc choosing to remain in the Old West with his family - and Marty Jr choosing to go back in time to the 1980s and remain there. Granted, the latter scenario isn't as well into the distant past - but it's still to an era from before Marty Jr was born.
I wrote a story called
Like Father Like Son, which actually addresses the issue of how Marty Jr and his friend, Harmony (who, BTW, is Jules' daughter), are envious of their parents' era - and they wish they could be teenagers in the 1980s. They resent how some of their peers laugh at them for listening to '80s rock music, and even how some members of their parents' generation seem to take issue with Marty Jr and Harmony listening to "their" music. They resent being made to feel like they are somehow abberrant or not normal just because they listen to music that came out before they were born. So they end up going back in time to 1986. Doc and Marty do end up letting their offspring stay for a week - but they ultimately end up having to return to 2016.