Someone I know runs a startup which just got an acquisition offer which would have given him $5-7m, a few years out of college with the acquirer was paying 1.1x their current valuation. He chose to turn it down since he thought his investors (one of the top few firms around) would find him unfundable for future startups. Instead he's choosing to 'swing for the fences', something which may or may not work given their current momentum.

Several lessons in there, including not raising at too high a valuation that limits your exit options.