Speaking with experience from one who lost their spouse to cancer, I would spend as much time as possible with my kids, family members, and friends. I would continue to take them fishing and host as many dinners and cookouts as physically possible. When I was reaching the point where I couldn't live a "normal" self sufficient life, I would seek out some fentanyl and buy a bottle of the best scotch I could afford, crank up some RUSH, and kick back in a comfortable recliner.
I wouldn't expose my kids to the roller coaster of emotions that go along with terminal cancer treatment just to gain a few more days/weeks/months. I would go out with as much dignity as I could possibly muster.