I guess this saves anyone from posting a poll on whether we ride for fun or to save gas! Seems pretty unanimous we all ride for the pure enjoyment of it and the gas mileage is just a pleasant byproduct.
As far as the night riding, I greatly prefer to ride in the day. I don't care how many lights you add, how clean they are, and how well aimed they are, you do not see as well at night. As someone else mentioned, there are a lot more critters that come out at night. Also, statistically there are a lot more drivers under the influence of (fill in the blank) at night. Now, if it was a beautiful, starry night and everyone was going out for a coffee or ice cream, I wouldn't hesitate to take the bike but I simply don't routinely ride at night.