Redwood is always a wood of choice, but the price in material is out of the park. In my area, PT wood for a deck can be figured at about $3.75 a square foot, Redwood is about $15, and cedar is about $12.
All these species will turn gray and will last about the same period of time. Redwood is so spongy and soft like cedar. I think that is why most are going to PT, but that will soon end.
I have found that PT wood needs to lay out after construction for all the chemicals and juices to leach out or evaporate before any coatings are applied. In my Area, a deck is dried out during the summer in about one month. I always tell my customers that the liquids will evap and if you paint/stain too soon the evaporation will also take the stain with it. Its like adding water to a sponge already full. Regional areas will differ on drying times.