Wind over a large area is far more constant than you might expect the problem is you need a vary large area (east - west coast) to see this.
http://earlywarn.blogspot.com/2010/04/averaging-us-east-coas... Still the major advantage to wind is it's the cheapest power out there. (Yes lower than coal, nuclear, hydro, etc.)
PV Solar is also vary steady in the areas you would put it. (AKA not the South Pole.) Storage is useful, but transporting power over distance is much more useful than you might think.
Finally, Hydro has a lot of built in storage allowing you to double output for weeks at a time.
