Clydesdales/Athenas (200+ lb / 91+ kg) - Road Bike tire size?

Been test riding relaxed geo road bikes. I get stange looks when I ask about Cyclocross bikes... None in stock. So I've ridden Cannondale Synapse,Trek 2.3, ect. I'm concerned about My 215 lbs on 23mm tires. I asked a salesman that was a heavier, old guy like myself about this and he said "When you wear these out go to 25mm tires." I said "What about 28's?" He replied "There isn't any advantage for them over 25's."

Speed is secondary to comfort for me. The roads I ride are rough textured oil and chip.Would the lower pressure of wider tires benefit me?

I've ridden 23, 24, 25, and 28mm tires. In a blind test, I doubt I could tell one from another... It isn't until I get to 32mm tires that I feel much of a difference.

I have road bikes with 23s and 25s and a cross with 28s. I weigh 250. It is important to run lower air pressures with wider tires or you won't notice the smoother ride. At 215 I would be more concerned about the quality of the wheels than the size of the tires.

The cross with 28s is definitely the smoothest (it also has the longest wheelbase), but it accelerates and climbs more slowly. Once up to speed on the flats there's not much difference in pedaling effort. I would keep looking for cross bikes to demo. If I had to have only one bike it would be my Ti Lynskey Cooper CX with two different wheelsets.

Cross bike geometries vary quite a bit. Some have higher bottom brackets and to my taste don't handle as well as road bikes. Some have slower steering. The cantilever brakes were much harder to set up than road calipers, but once dialed in they're more than adequate.

You may also want to consider light touring bikes. They will generally clear larger tires and would be a better solution if you don't plan on riding trails.

As mentioned, run lower pressure with wider tires or you won't notice a difference. Also, some road bikes won't have clearance for 28 tires.

Definitely try to find one of these"
http://www.trekbikes.com/us/en/bikes/road/cyclocross/steel_cross/erwin/#/us/en/model/details?url=us/en/bikes/road/cyclocross/steel_cross/erwin

If I had your budget, I'd be building my own starting with this frame:
http://www.amazon.com/Origin-CX700-Cycle-Cross-Bicycle/dp/B004RS0B78/ref=sr_1_3?s=cycling&ie=UTF8&qid=1309741960&sr=1-3

I have 23 Armadillo's on my trek 1.1, haven't had any issues. That said, I have 38 Armadillo Crossroads on my Specialized Tricross Sport and it's much more comfortable to ride. The 1.1 is faster, but the Tricross is what I prefer to ride.

If the frame will take them - Schwalbe Big Apples - low rolling resistance, high puncture resistance, and smooooooooth.