Jul 17, 2011 - 11:53 AM
One of the best books on hiking trails in the Bernese Oberland is Kev Reynold's "Walking Switzerland: Bernese Alps". I don't recall offhand if he has specific maps inside but he describes the routes very well.
Once you arrive in the BO you will be able to get trail maps very easily. There are a variety of free maps for easier walks (start looking for these at the tourist office) all the way to detailed topo maps available at all the larger villages (such as Wengen or Mürren).
Depending on the walks you are planning to do, though, you really don't need maps. All the routes are very well signed.
That said, if you want to buy maps in advance for specific walks, a good resource is www.walkingswitzerland.com. Go to the section called The Walks and choose the one(s) you are interested in. There will be a walk description, pictures, and links to maps you can purchase.
Finally, another good on-line resource is activityworkshop.net. They have a section that describes walks all over Switzerland, and this is the definitive source for the route description for the trans-Switzerland Alpine Pass Route. Here's a link to the overview of hikes in Switzerland http://activityworkshop.net/hiking/switzerland/index.html