I certainly over-prepare, but I try not to over-plan. I spend too much time here even when I have no idea when/if my next trip will happen, but when I actually get around to planning a trip, I make myself write it all down so that I can see if I start to overschedule a day. I probably go through a thousand options, but try to make the final product fit our laid-back travel style so it's not stress-filled once we get there. 

Like someone said it makes it last a year.I can't stand around wandering what we should do next-though plans can ALWAYS bechanged.Especially when my children are involved.