[Asphyx]

While all of those will work I really suggest you spend the money on either Garmin or Tom Tom....

(I'm not on sprint so I can't say how well Sprint Navigator works)
Google needs to have a data connection to retrieve maps. You lose data connection you have no map displayed! (Not a problem unless you go into rural areas where data coverage still is sketchy)

Both Garmin and Tom Tom lock up just as fast, you can fit the entire US map on a 2gb memory card (I have both installed to the same memory card 8gb), meaning you never need to download maps except to update the old ones from last year at a time of your choosing...

and I think those are much more driver finger friendly than Google...

I tried iGo in a rom long ago but I never used it enough to comment on that app.