This is the book to buy if you are staying in the the south of Tenerife or on La Gomera. La Gomera is only an hour and a half from Tenerife by ferry, or only 35 minutes by hydrofoil. The schedules allow you enough time to get there for a day's car touring or walking.
This book is divided into two parts. The Southern Tenerife section has car tours covering the whole of Tenerife, using Playa de las Américas/Los Cristianos as a base. It also describes several spectacular walks but only in the south of Tenerife.
The Gomera section describes tours and walks all over that island (which, incidentally, is the author's favourite of all the Canaries). Gomera is still unspoilt, and its mountainous terrain affords some really challenging walking.