I just downgraded from the $700 Garmin to the $290 Garmin.
I travel ALL over the country on a regular basis... and I seriously mean some wierd ass places you aren't likely to ever get to like remote Indian reservations... heavily forrested Vermont where you only have dirt roads... the distant sticks of the Dakotas.
I can't peak for Tom Tom... but I can tell you that the Garmin I got has been a life saver... and I hear Tom Tom is just as good.
I down graded from the $700 to the $290 because like you I don't need the bells and whistles. I don't even really have a clue what blue tooth is. All I need is voice directions and verbal street names... and the cheap unit does that just as good as the more expensive one... and given the odds of me accidentally leaving the unit in a rental car, getting it chewed by my beagle puppies (already destroyed one GPS) or whatever other kind of mishap can happen... the cheap unit is actually the better choice for my lifestyle. It does everything the expensive unit does that I actually need... and it does it just as well.