The "alternate" could be called purgatory, but, to me, it's the road the cast wished they had chosen. What intruded on that made-up reality is the love and connection each had with the other cast members. Then that life (real life) was preferred.
I think that Jack worked out alot with his son, but in the end, when he got to work it out with Christian... excellent.
I believe that Frank, Miles, Richard, Kate, Sawyer, and Claire did live a life after taking off in Ajira plane.
You are right about Hurley and Ben.
Rose and Bernard died on the island. As did Vincent. But eventually, they all died. Boone, Shannon, Charlie on the island. Locke at the hand of Ben. Ben and Hurely on the island way in the future. It didn't matter when they died, they were all there, in that church, to be together because (and I really believe this) those 100 days spent together were the best days of their lives.
I loved the ending.
I also believe that protecting/saving the island meant protecting/saving the world.
I heart Vincent.