It might be enough just to list the members of this all-star Euro-American big band, but that's too easy; it tends to diminish the large-scale, episodic pieces written by Swiss pianist George Gruntz, which sometimes resound in the jazz orchestra tradition (trumpet, trombone, sax, and rhythm sections) and other times treat the ensemble as 18 individuals taking turns in the spotlight. Gruntz's most recent record is four years old and features a different lineup, but that's enough to recommend this date--last stop on a rare North American tour--as this fall's most unmissable concert. Now the easy part. The personnel includes alto saxist Lee Konitz and tenor man Joe Henderson (each among the most respected reed stylists of his generation); a U.N. trumpet section of Briton Kenny Wheeler, Italians Enrico Rava and Franco Ambrosetti, Manfred Schoof of Germany and America's Marvin Stamm; trombonist Ray Anderson; Howard Johnson on tuba and baritone sax; Bob Moses, an impressively mad drummer; and vocalist Sheila Jordan. Several of these players are rarely in this country, and certainly never in such abundance. Tuesday, 8 PM, Organic Theater, 3321 N. Clark; 283-0531 or 898-5856.