Las Vegas is convention central. Orthodontists go there as well as architects. Computer geeks and gynecologists, TV preachers and township clerks, postal workers and pathologists. There's an abundance of good hotel rooms, cheap eats, agreeable weather. Coming and going is reasonably painless. There's golf and gambling and ogling girls -- showgirls of unspeakable beauty -- and, of course, the mountains and the desert and the sky.