Thanks for sifting through all of this. Lots of great ideas here. 

I think the rule for stuff like what you had for breakfast or where you're standing in line has to do with adding a bit of color to your tweets. For example:

A: "Waiting for my flight at Ronald Reagan airport."
could become...
B: "Ronald Reagan airport has the most comfortable seats by the departure gates. Maybe I'll skip my flight..."

Both carry the same idea, but example B invites interaction. A twitter feed of posts like that would be like eating cotton candy for dinner, but in the midst of sharing helpful links, retweeting what you value, and microblogging on your niche topics, a little something like that should be well and good. I think of it as doing unto others what you would have them do unto you. 

Not to drop in some shameless self-promotion, but I also just shared my personal rules for twitter in my monthly e-newsletter... :)