In order of preference:
1. Mark greenspace and parks: I choose my route primarily on scenery, I bike commute for my physical _and_ mental health. Also it is sometimes convienient to short cut through parks and open space.
2. Mark locations of LBS's: In my city its not a big deal there are only two. But some of you gots lots!
3. Give suggestions as to best crossing points over rivers and highways: The hardest part of planning my commute was finding the safest way across a gulch and a freeway. The first few rides were a series of experiments of the best combinations of crossing points. I had a very scary experience on a bridge that turned out to be both longer and narrower than it appeared in a car.
4. Mileage on the major trails and routes. or a table with distances between landmarks.
5. Phone numbers of cab companies somewhere on the back.
6. A copy of the local bicycle laws from the Motor Vehicle code. (small print)
7. Locations of Bars