Looking at a GIANT TCR COMPOSITE 2 but am nervous about the wheels.

Any idea if the Shimano R-540 Areo Wheelset will hold up to a 6'5" 250lb guy?

Used to be, anyhow, and I seem to be headed that way again...apparently the beer-and-ice cream diet isn't the long-term answer.
As far as wheels go, though, I rode thousands of miles at 240 and above, and I invariably had trouble with fewer than 32 spokes. We have a couple of good wheelbuilders here, and occasionally one would insist he could whip out some lightweight wheels that would do the job. Never happened. I suspect most mechanics, who like most cyclists are <150 pounds or so, don't really have any concept of what it takes to hold up a Clydesdale...
Most of my riding now is on a pair of Rhyno Lites laced with 36 14ga. Wheelsmith spokes to Deore XT hubs (it's on an Atlantis, w/135 spacing, so I use an MB rear hub). Only very minor truing in about 3000 miles. I also have a backup set, some old 32-hole RSX hubs laced to Velocity Deep V rims. They seem plenty strong, too, but they're heavy.
It's tempting to go lighter, but I've tried it often enough that I'm able to resist. If anybody says he can build you something like an 18- or 24-spoke wheel that will last, I'd ask him to guarantee it.

Go with this wheelset,Colorado Cyclist sells this 14 spokes(ultegra or dura-ace) :)

I am 230 and have broken many wheels. Spinergy spoxs, xeros, Rolf Pros, Mavics and I finally gave up on light wheels. I am now riding Chris King hubs 32, 14gaug, brass nibs and an offset rear rim. I have not had any problems with them. Don't go with lighter wheels because you will have problems down the road and will be upset.

Looking at a GIANT TCR COMPOSITE 2 but am nervous about the wheels.

Any idea if the Shimano R-540 Areo Wheelset will hold up to a 6'5" 250lb guy?

I've had good luck with the Ksyrium Elites, and I'm 6'4"/220 (on a good day). If that's too chi-chi for you, the CXP33's already recommended are fine, or, really, anything that you can get in 36-hole form will work well.

Looking at a GIANT TCR COMPOSITE 2 but am nervous about the wheels.

Any idea if the Shimano R-540 Areo Wheelset will hold up to a 6'5" 250lb guy?

Im riding OP's with CK hubs, Therer 32H and laced 3 x with 14/15 guage spokes. Im hard on um and they hold up great. You wont need anything more than that IMO.

Go with this wheelset,Colorado Cyclist sells this 14 spokes(ultegra or dura-ace) :)

I've got a set of the CXP33 Mavics laced 36-3X with straight gauge 14s and Ultegra hubs and they are holding up well for me. Previously I had broken several spokes in my stock Lemond Poprad wheels. So far no truing has been necessary. I ride mainly pavement with some gravel roads and light trails mixed in. I'm usually anywhere from 225#-235#.

Looking at a GIANT TCR COMPOSITE 2 but am nervous about the wheels.

Any idea if the Shimano R-540 Areo Wheelset will hold up to a 6'5" 250lb guy?

I'm in the same weight class as you and ride M540s on my commuter bike - I haven't had to touch them in 6 months. They're light(ish), reasonably stiff and reasonably aero with teh low spoke count and bladed spokes. My LBS guy reckons the R-540s are just as strong. That said, the smaller diameter of the M's vs R's might be a factor. On my road bike I run CXP33s, 32H, 3x tied and soldered on campag hubs - these wheels are BOMBPROOF!