Unless you remove the soluble limescale from the water you wash your car with, you are always going to have watermarks if you leave it to dry on its own, that is unless you have a water purifcation system (reverse osmosis system) similar to the pole system that window cleaners use.
Using a chamois is the best way and does not take long, especially if you use a "wet on & wipe off wax".
http://www.turtlewaxuk.com/prod.asp?Partcode=FG5197
I use this for interim washes, and it assists with removing the water from the car,
I can dry the car in less then 10 mins using the meguires microfibre waffle weave chamois and the product above, the combination works really well and leaves no water marks.
Full a full washing session i will use the meguires 3 stage treatment.