I'm the same way. I just had a conversation on the phone with a female friend who is married to an AS man. Both he and I like spontaneous travel, and I was trying to resolve why. My thought goes something like "If it's spontaneous, I don't know what to expect. Because I have no expectations, I also don't have loss of expectations when we do something random on the way." I'm not sure that's the whole of it, but it does feel very freeing to be outside the constraints of a really well-planned trip.