I don't like the suction cup mounted holders either. We have the opposite problem of the weather getting too cold and the things just fall off.
I like the cupholder-based units, like this:
http://www.amazon.ca/Satechi-SCH-121.../dp/B006VY8C6S
They don't fall off the glass. Also, in Ontario, it's a bit of a grey area as to whether you can mount electronics on the windshield. A cop can cite you for obstructed view at his/her discretion.