This is a terrific little reference book. "Unbelievably good deals and great adventures that you absolutely can't get unless you're over 50" by Joan Rattner Heilman, 2007-2008 edition, McGraw Hill, 2007, will set you to dreaming about what you're going to do with all that free time when you are retired. There are 19 chapters on travel, education, sports, shopping, etc. Chapters 2-12 actually deal in some way with travel--lodging or airfares, tours, cutting costs, etc. This author doesn't want you to pay sticker price for anything. Always ask about a senior discount.
If you are a single man over age 45 and a great dancer, consider being a "host". You can cruise for (almost) free, working 3-4 hours a day. All you have to do is not get romantically involved with any of the passengers.
This summer at Lakeside I met a kite-flying teacher who was wildly enthusiastic about the Evergreen bed and breakfast club, which is featured in this book. It's for people over 50, has 3,500 members and 2,000 host locations. A couple pays $15 for each overnight stay. The club dues are $60 (single) and $75 (couple). Check www.evergreenclub.com.