Research local laws. It's going to vary state-to-state. Most interstates don't allow scooters because of speed restrictions and general safety concerns. 60 miles a day seems a lot to log on a scooter - why not go for your motorcycle license and get a more powerful bike? Then you don't have to factor in extra time for your commute, and your routes don't have to be planned out to avoid highways. And always remember that any inclement weather is going to be 10 times worse than it would be if you were in a car. :-)

You need to be motorcycle endorsed for any scooter over 50cc. Those little Vespas and Metropolitans are of the 50cc variety. If you're going to commute, you should really be looking at a larger scoot, something along the lines of 400cc. I ride a Suzuki Burgman and could not be happier. These run a little more expensive, but even with today's gas prices I use about $8 every two weeks. At 60 miles a day you'll use more, but it will pay for itself regardless. Interstates do absolutely allow scooters, provided they can keep speed. My ride tops out at 100 and I can easily keep up with any traffic. When it rains, I get wet. If you have a good rain jacket and wear a helmet (which you always should...your skull is no match for asphalt), it really isn't a big deal. No matter what size scooter you choose, I can't emphasize enough how important it is to get properly trained. A good course takes only a couple weekends and will make you much safer and more confident on the road. Good luck. I haven't regretted getting my scooter for one minute. I addition to saving gas, it's just a hell of a lot of fun. http://www.suzukicycles.com/Products/AN400K8