If cost isn't much of an issue, then I can see going with Trex or similar. The low maintenence aspect is certainly attractive. However, when I built my deck last year, I did some price comparisons with 12'- 2x6 PT lumber and found Trex to be between 3 and 4 times more expensive. That's a lot of bread on a 600 square foot deck. As for the "I'll never have to replace it" argument, consider that Trex is not structural - you must still use wood for the joists and sub-structure of the deck. Eventually, these will develop problems under the Trex. Is anyone going to remove Trex, rebuild the deck structure and put the old Trex back on? I doubt it.