In Monaco, that seed-pearl-by-the -sea, under a glowing golden dome is the queen of all the chance parlors-- Monte Carlo Casino. Since its inception in the grim days of 1863, to help prop up the Grimaldi fortunes, which were down to a threadbare plush throne on a slime covered rock, to the Princess-blessed present, glittering Monte Carlo has reflected the tastes of the fast-buck tourist from royal roulette to common craps. The authors make it a spicy trip and report it here with zest and all that aristocratic gossip that always gets suppressed in royal biographies. The Casino has had its ups and downs-- literally up from the sea and surrounded by reclaimed land and down to dark days, when the kingly and courtly feet swung off the rigid track of Edwardian vacationing routes. Nevertheless, prevailing Society always has, through the decades, washed up at the Casino's door. Elsa Maxwell brought them back in the '20's (she found them a beach for the new sun worshipping set) and latterly Onassis sailed in (he brought up a majority of Casino shares in a pet when denied renter's privileges to a piece of prime Monacan soil). Paralleling the gametable talk is a swift, running history of the Grimaldis. There was another American princess, Alice Heine, who brought culture in the form of an internationally famous ballet and opera which she chiseled out of Casino directors, beating them at their own game, so to speak. It's all here and it's winning entertainment as well as perceptive social history with a light touch.