You can go to google maps and select bicycling to see bike routes and lanes. Also you can go here to request a paper copy of the MAG Regional Bike Map.

MAG Publications

It looks to me like you have several choices. Straight down Scottsdale/Rural may or may not work for you. I've ridden both the Crosscut Canal and Indian Bend Wash and they were fine. Don't know about 68th St. I can't tell you much about south of Tempe Town Lake either.

Good luck.