Pavers: Pavers, depending on your location will heave and fall with the soils. In our area, the wet times of the year cause the soil to become saturated and rise, then in the summer, it falls. So, if you go pavers, I would recommend the below grade concrete foundation with rebar and then apply your pavers on this form. This will still move around. This could be quite expensive. I have seen very few concrete patios that have not cracked and become dangerous.
Synthetic Lumber: Trex is a new synthetic material introducted to this area about 5 years ago. A local Payless Cashways had a model deck made 100% of this material for customers to see and make a decision on. They did not carry the lumber but would special order it if someone wanted the material. I understand why it was not carried because of its high price. Anyway, last year, the deck was removed from the parking lot. Knowing the Pro Desk Personnel, I inquired as to its demise. I went out to see it and it had buckled, bowed, and contorted beyond repair. Trex people constructed the deck. I instantly knew that this was not a viable material. Living in Texas, the heat and sun are devestating on stuff and I figure that it just cooked. Those nice new and fancy and expensive white vinyl fencing are also sucumbing to the heat too, many are yellowing.
I must interject here, I am a deck and arbor contractor. I only build with wood. 95% is wolmanized pressure treated wood, the rest is mainly cedar and redwood. I WILL NOT USE ANY SYNTHETIC MATERIAL AT ALL!!!!
Wood: In Texas, material costs per square foot: pt wood $3.50, cedar $8.00 + square foot, redwood $12 a square foot if you can find heartwood.
Now, all three are good for outdoors, all three turn grey on their own. All three can be stained after sufficient drying time. All three will last 10 to 15 years.
Many decks last a shorter life span due to neglect. Neglect in not cleaning out the throats between the boards. Debris will fill in those cracks and cause premature rotting. I always every spring and fall pressure wash my deck and clean out those throats. Decks that are built with spliced boards will rot sooner in the joint section, therefore, I strive to make all decks with one long board without splices. Many people allow they water sprinkler to throw water on the deck. In our area this will cause any wooden object to turn black. Its the floride and chlorine. I can drive down a street and find many fences look like a hand of cards by the black stain from city water. This is why they make 180 and 90 degree sprinkler shields.
I have gotten on a tangent here, but I think I have given you something to think about. Any other questions post them and we/I will be happy to further expand on them.