Big selection of mounts at Semsons. For your TomTom 720:
http://www.semsons.com/togo5272920m.html
I have tried 3 different mounts for my Garmin 255W:
-- The vent mount is handy and provides a nice location, but not solid enough for my taste
-- The cupholder mount puts it too low in my 05 Ford Escape, but is the best solution I've found for my C6 Corvette
-- Very pleased with the CM012 friction mount in my Escape
They also have a hardwire cable converter for Garmin:
http://www.semsons.com/ganutohaca.html
Maybe they have a hardwire kit for your TomTom.
Cannot comment on mounts for a Toyota (maybe Avalon, maybe Venza) because I don't have one yet. But hope the above helps. BTW, I have ordered online from semsons twice... no issues & quick delivery, and they notify by email when your order ships & provide a tracking number.