Actual maps are excellent resources for developing and verifying the details of your family history map. Plat maps, in particular, are helpful at confirming or sorting out identities because they include names of owners and boundary lines, keeping genealogists from confusing John Smith and his descendants with nearby Jon Smythe and his descendants. Many old-timey plat maps have been digitally reproduced and are available via Google Images or Google Books. Genealogy Insider also suggests visiting WorldCat to locate map books that are not yet electronically available. Older maps are especially helpful because boundaries and city/town names have a way of changing over time. According to the United States Census, pinpointing the exact location where your ancestor(s) lived can more easily help you to identify the nearest government records office, which usually yields a ton of great information.
Also, if your goal is to create a book of physical maps of ancestors' lives, it's simple enough to locate historical renderings via online map collections, like the David Rumsey Map Collection or The Library of Congress, to name a couple. Many university systems often boast similar resources, so try those nearest the area you're researching for the maps you desire.