I know there are plenty of threads saying the pluses and minuses of the different GPS apps. I was just wondering if anybody has used any of these apps around the DC area? I know different apps really vary based on where you are. If I'm driving down an interstate, I would expect every GPS app to be able to handle that well, but how about city driving? Sometimes you have to make a lot of quick turns so any delay or loss of gps signal can really throw you off. I have a stand alone TomTom unit that is starting to get a little dated and I'm thinking about upgrading. Also, do you really have to mount it to your window for it to get a signal or does it work fine just sitting in your lap or in the passengers hands while driving?