Which deck things is best? We are going to replace the top boards of our deck...

We are going to replace the top boards of our deck and I am not sure which material is the best.

The deck is considerable, 15 feet x 45 foot, and is up high sour the main smooth. Underneath is a patio.

The deck structure below the top boards is fine, the problem is that the previous owners went over the outmoded boards with a shrunken second layer of boards and presently all the boards are rotting discouraging.

I am all in the region of keeping costs down as much as possible, and I don't mind the look of pressure treated lumber, but I saw something about leaching arscenic and children?? I also read that composites can't be used this dignified up...

Ideas?
Winter Watering, protection Northern CA?
Answers:    When we had our deck built they said they couldn't use composite for the structure since composite 4x4's aren't strong satisfactory when they get above a convinced length (I can't remember how long), but that composite can be used for all the horizontal surfaces and railing.

Our deck is about 15 foot off the ground and uses composite.