How to finish cedar deck chairs
Nope.  Don't use Water Seal.   The main issue is that cedar is a pretty soft wood, and it wears.  No matter what you put on it, the wood beneath will wear, and it will look like a leper with a sunburn.  

What you want to use is an oil.  @Jeremy above suggested Australian Timber Oil, which is as good a solution as any.  The idea is that oils will penetrate the wood, and when the outer surface wears off, it doesn't take the finish with it.

Of course, you'll have to freshen it every few years, but with care, an oil finish is going to last the longest.