An NAHB publication billed the 1988 Annual Convention and Exposition as the "largest building products and services show held anywhere in the world, bar none." Shows in Germany and France are reputedly much larger, but who cares. If you like big, you'll love the NAHB convention. Even if you don't, you owe it to yourself to witness at least once this annual rite of the American building industry. You can't help but be entertained, and to learn something useful as well. You'll also be heartened to find that builders–large and small– from all over the country have to contend with cracked concrete, late subs, complaining customers, and so on. For those of you who didn't make it this