It would be fairly easy to designate flight lanes so to speak where use of jetpacks are allowed. Perhaps restricting them to use over sidewalks primarily for instance and regulating speed much like you do with cars in residential areas.
A jetpack only moving at a max speed of 25 MPH should be fairly easy to control for anyone and since we already have automated cameras and guns regulating speed and taking pictures of anyone who breaks laws it would not be too hard to include the sky in the area being monitored.
Honestly though, think about the sport applications here. We pay Atheletes so freaking much money that 100k per athelete for a jetpack sport of some kind would not be that expensive and it would be FREAKING AWESOME. I mean seriously just two teams with jetpacks that have a goal a decent distance apart and a beach ball they need to get in the goal (or block from getting in the goal) only by hitting it with special sticks.......would be fun to watch.
As far as transportation I think anyone should be able to use a jetpack on their own private property and then slowly cities should open up legal areas/lanes/streets or flyways for jetpack use as well as it becomes more popular. If only a few people still have jetpacks you could petition for specific jetpack flight paths (Say to and from work for instance).
The range eventually would need to be expanded though in order to make a big difference on commuting. Eventually though you could easily make a "jetpack highway" over water and mainly unpopulated areas that could turn a 2 hour commute on the freeway into a 30-40 minute commute in the air.
I live in the Bay area and getting from San Jose to San Fransisco takes about 2 hours during the commutes but less then an hour with no traffic traveling 60-70 mph. If Jet packs had a 1 hour charge you could do the trip in a bit less then an hour easily.....that would be worth 100k to many people pretty fast actually just in time saved etc. That of course is saying that the fuel is not massively expensive. Ultimately the best bet would be to have it be based on electrical charge which you can power up over night or during the day at work.
To really start to be useful you need the packs to be chargable and have at least 1 hour use at a top speed of 68 mph or so. If the battery packs are replaceable you could event take a decent amount of time to recharge them, or even have places you can just trade in your pack for another for a small charge (recharge stations so to speak). This could allow someone to travel very long distances with very little downtime by pit stopping every hour or so.
Want to go from SF to LA? Just plot out a course from recharge station to recharge station and make the trip in 7 hours (6 hours of flight with 5 pit stops along the way).
I see endless applications of this technology