I was there...
...four and a half years ago. The money was almost the same, the benefits equivalent, and I made the grievous, literally life-changing error of going with the first offer without asking for a bit more time. Had I done that, I would have approached the team managing the process for the position I really wanted, the one where my heart was. They offered it to me right after I accepted the other offer, and I was too self-destructively ethical to go back to the Blue Meanie, and say "thanks but no thanks."
I am now crippled due to a work-related injury, stuck 3000 miles from family and friends, financially destitute, and uninsurable and probably unemployable.
The morale? Screw the "sure thing" and go with your heart.
