My wife wants the seat down all the time. Two good reasons:

1. It helps avoid an unintended midnight fall into the depths of the bowl.
2. Keeps the family dogs from drinking from the toilet and making a wet mess everywhere.

I try to keep up with the rule of always leave the seat and lid down.............but I figure I am only 80 % compliant.

If the lid is up its likely my fault even if its not. I have on occasion dropped the lid after use to announce..."THE LID IS DOWN" always a proud moment when I get it right.