This is important since there are only 100 user defined waypoints. Once a route is enabled you get turn by turn instructions from the road sign page and other places. While the Street Pilot won't do automatic routing it will find a location by address or intersection or poi with the right metroguide maps installed and you can easily create a route just by rubberbanding the line drawn from where you are to where you want to go. These units will run off of 12 volt power or 6 AA batteries. The Street Pilot will get up to 16 hours on a set of batteries while the color unit gets about 9 hours if you keep the screen as dim as possible or about 2.5 hours on maximum brightness.
Color takes a lot of power.
Other Handhelds Garmin makes two units that they call handhelds that have a very large display. These are the GMap175 marine unit and the GMAP195 aviation unit . They weigh in at a whopping 1.4 lbs, like the street pilots, and use 6 AA batteries with an expected battery life of about 10 hours. They also support a rechargeable battery pack. While they can be held in your hand you wouldn't want to carry them very far.