Cycling or spectating? I went in 2005 with my bike and rode all over southern France. I stayed near Rennes-le-Château. The Tour came through and on that day I rode south into the Pyrénees and up the Port de Pailhères to see it go past at that point. Logistics involved with that of course involve getting your bike over there and then planning at which point you want to see the Tour.
Very basically, figure out where you are going to be and then check the TDF route and pick where you'd like to intersect it. Check a bunch of guides and the web and try to find a B&B or something that will put you up for the night (unless you can just ride to and from where you currently are at). This close to the Tour, many/most will be all booked up, but you may get lucky. You could drive to and from via rental car, but just note that traffic gets backed up and then blocked a good number of hours before the race comes through and getting to the top of a mountain that way (and having a place to park) requires an overnight in the vehicle if its an important mountain.
Easiest for sure is by bike (unless you have a place in a finishing location). You can much more easily find a place to spend the night within range of any intersection point that you can ride to, ride there early in the am, wait and see it go by, and then ride back.
Good luck! Seeing the Tour in person (not to mention riding a good portion of one of the routes) was an incredible experience. Even better if you can ride up one of the HC mountains and then experience the crowd up there, but honestly, any way you see the Tour would be unbelievable. Its nothing like seeing it on TV.