An uncommon guidebook"" is a bright display of all the ""happy differences"" this city offers to its inmates- as well as the outlanders, to assorted age groups, and income levels. If the selection is admitted shaped by personal tastes, most of the comments are on target and entertainingly styled. With a little history in the background, there are suggested prowls through the various parts of the city and their indigenous peoples and provender; museums; restaurants- a few of each nationality at each price level; bargains, from the big basements to the discount houses; advice on the feeding and entertainment of children; special shops from foods to fashions; music, theatre, the arts, night life, and a special calendar of events around the year. The Etcetera at the close will tell you where to get anything from a left-handed check book to kangaroo hides to a portrait of your dog-at Chi Chi Chien. A fascinating inventory and itinerary of this city's many attractions and diversions.