I tend to plan and organize, but there is a lot that I don't plan on a bike tour... (It also depends on length of the trip):

What to bring?
- I have a pretty well developed equipment list by now, so by now for a week tour, I'll wait until two nights before I leave and pack things
from the checklist. For a multi-month trip, I'll go through that list a bit more in my mind and end up renewing some things (e.g. tent)
as I think through them.
Where to go and where to stay?
- I don't plan my detailed route and I generally don't plan where I'm going to stay. On a week-long trip I'll go through a site like
motelguide.com and get a list of towns that have motels. I'll also have a rough idea of the route though will switch off specific roads
on a day by day basis. On a multi-month trip, I won't plan any places to stay or routes but will know roughly directions and create a
"mileage budget" to keep track of approximately how far it is along my main goal and hence what sort of rate I expect to do per week.
- I avoid making reservations unless it is a known crowded area or it is my first night off a plane.
Additional planning?
- On a multi-month trip, I'll make sure I have immunizations and visas in place. Shorter trips are less likely outside US.
Background info?
- On a multi-month trip (to a more remote location like across Russia or around Australia), I'll have read others journals and general
tourist info about the places I'm going through.