I enjoy being a player almost as much ias I enjoy being the GM. Recently, I had an idea for my campain: The players discover from a very early stage in the game that they are destined for greatness when a dream god tells them. They dont believe it, until the signs he fortold in there dreams come true. So from that moment on, they're faced with various challenges; nothing planned out, that way the players have the most influence over the game. I got countless possibilities in case they wanna do something dumb.

But, I wanted to know if I should do a regular game, or a game that could last forever. I read in the Pathfinder Core Rulebook that the best way to keep going past 20th level is multiclassing so i figured, why not. So I figurd i get advice from you guys, listing the pros and cons to short and long games.

Average Game (level 1-20)

-Easy, fast paced interest in game
-Less work for me, the GM

-Regular; Unoriginal (Game-Legnth wise)

Extended Game (level 1-unknown high level)

-Players could get emotionally attached to characters
-Very in-depth, realistic character growth and development
-It would be a story to remember
-Could inspire post-game ideas (Fan-stories, etc.)

-Too long, and could lose character interest
-A lot of work for the GM

So before I go with my idea of an epic, long campain, I wanted your opinions.