Invisible Glass markets a brush that has a triangular microfiber pad on a ~20" stick.

It's roughly $15 at your favorite auto parts chain, and at first I thought $15 was outrageous but after cleaning the windshield with the tool and NOT straining my back, it was well worth it.

I use the aerosol Invisible Glass cleaner, just spray that liberally on the pad and go to work.

Works like a champ and the pointed pad allows you to get all the way up against the front of the dash.