I used to use Streets and Trips, but when I got a new GPS over a year ago, I found a Garmin Nuvi that has route planning along with lifetime map updates and traffic. It will route up to 100 locations per run. It's not as easy as entering the addresses on a PC and optimizing, but it has saved me countless hours on the road because the traffic app helps to reroute when issues come up.
Philadelphia Based, covering Eastern Pennsylvania, Delaware, New Jersey, Maryland