If you want to get some exercise, see the sights, explore, investigate and generally just poke around the Napa Valley, try one of these books that, by definition, will get you off the beaten path to see and enjoy some of the hidden territory most people never get a look at.

Great Day Hikes In & Around the Napa Valley
By Ken Stanton
Bored Feet publications ($14.)
If you want to walk or hike around Napa County, this is the book. Filled with basic maps, clear directions, interesting notes and area history, it is all the title says it is, and more.

Wine Country Bike Rides
By Lena Emmery
Chronicle Books ($10.95)
Easy to us, with clear maps, good directions and a minimum of fluff, this 110 page guide (which also covers Sonoma and Mendocino Counties) still has room to list and index stopping places (restaurants and so on) and wineries.