Fire Marshall Bill
Let me show ya somethin!!!
Their sons, Jules and Verne, create a huge problem, especially if we can presume the family lives in Hill Valley. These boys, who were never meant to exist in 1881, eventually marry and reproduce with women who, in the original history, do that with other mates. Same thing as Doc and Clara; the entire dynamic of the town changes.
The only way the four of them can get away with existing in the past is if they never interact with anyone. Fat chance of that.
You're right, Bill, this is a funny thread. I love discussing possibilities of time travel.
I think it would've been perfectly fine if they coexisted together traveling through time from a completely scientific aspect. Studying the future, past, whenever, but without really having a life anywhere or effecting anyone's life in any way. As long as they never reproduce and when they eventually settle down they do it in BFE away from everyone, her death in 1881 is technically accomplished. Sure Doc never officially died (well he technically does in the first movie), but by removing himself from time, essentially he just killed his life.
But since we're getting away from the thread:
Spiderman 2
Spiderman
The Amazing Spiderman
Spiderman 3
Frankly, I enjoyed The Amazing Spiderman. It's just that the first two films were done so well that it still isn't as good as them. Plus...Emma Stone

Spiderman 2 is up there with the best superhero movies of all time. It's a great story from hero to villain. And the end with the reveal to Mary Jane was done perfect.
The first Spiderman I just like overall better than The Amazing Spiderman. It could have to do with being original.
Spiderman 3 was just doomed from the beginning. A proper story involving Venom should take two movies. One where Peter finds Venom, uses him to destroy a villain and finally sheds him. The very end should have Venom finding Eddie Brock and that would lead to the 2nd movie. I think the root cause of the failure of Spiderman 3 was that they knew there wasn't going to be a 4th movie, so they crammed everything they could into one big mess.