I think that given the ability, most people would go directly to rewiring their reward centers to respond to something "better" that would dispense with our current overriding goals.
And do you have any evidence for that claim besides introspection into your own mind?
I've read short stories and other fictional works where people describe post-singularity humanity and almost none of the scenarios involve simulations that just satisfy biological urges. That suggests that thinking seriously about what you'd do with the ability to control your own reward circuitry wouldn't lead to just using it to satisfy the same urges you had prior to gaining that control.
I see an awful lot of people here on LW who try to combat basic impulses by trying to develop habits that make them more productive. Anyone trying to modify a habit is trying to modify what behaviors lead to rewards.
Part 1 was previously posted and it seemed that people likd it, so I figured that I should post part 2 - http://waitbutwhy.com/2015/01/artificial-intelligence-revolution-2.html