How can I get water marks out of a suede sofa?

I have a suede sofa and loveseat that are 3 years old. Over the years since I bought them my 4 kids have spilled stuff on them, drooled on them and just gotten them dirty. Usually I just take a clean cloth and some warm water and wipe them clean but this always leaves a water mark. It's not attractive and where I have had to wipe frequently, (like on the seats and arms) the suede isn't soft and plush anymore. It is kind of stiff. What would be a good method of getting these water marks out and restoring the softness to the suede?