Breaks on tickets, accommodations, ear rentals at 55? Yes, you not-so-old folks, if you join one of the three major senior citizens organizations listed here. ""And you don't have to be retired to join--just over 55.' To, get anything off from the airlines, Amtrak, or Greyhound, you have to be a bona fide 65; but while the same is ostensibly true of many museums, restaurants, and other rate-cutting establishments, ""if you show any identification that says 'senior citizen,' the clerk will probably not quiz you on your age."" All this smacks of trying-to-pass-for-under-twelve in reverse, but those who don't wince at the thought of being called well-preserved--as well as their unaffiliated, not-fully-benefitting elders--may find the book worthwhile just for the strategy it suggests. It doesn't do much more: the state-by-state, city-by-city listings are bulked out by citing one after another Avis office, Holiday Inn, etc.--inessential once you know which chains have a discount policy; most people are aware by now that museums regularly cut entrance fees; and nobody's likely to head for the Ponderosa Steak House in Springfield, Ill., because it offers 15 percent off (""except on 'specials'""). So there's a fair amount of deadwood here--along with, librarians should note, a bunch of discount coupons at the back (mostly redeemable for very little at very out-of-the-way places). But people who aren't getting the full benefits of age will find this an eye-opener, regardless.