Our daughter usually goes diaperless from after her bath until she puts on her jammies for bed. It's usually not that long, but sometimes it can last a while. She has one of those bath towels that has a hood on it, so she wears that between bath and bed.
I think it's good to go diaperless now and then... but she's not potty trained yet, so she can't go too long or else there will be an accident.
How often do your kids go diaperless?