If time is tight, or you just like to arrive at a holiday destination very well prepared, a guidebook is a valuable and important investment. So choosing the right one is crucial.
Whilst I suspect that "Time Out" and "Lonely Planet" books probably sell in greater volume, having looked through them both I'm extremely glad I opted instead to use this Eyewitness Travel Guide for my recent trip to Paris. It helped me make the most of my trip.
As with most guidebooks this breaks down Paris into a series of districts - but then very clearly labels the key attractions, how to find them and even proposes short walks that will enable you to get the most out of your time in that area.
Accepting that flicking between pages as you try to find different streets, where to eat, where the nearest Metro station is (etc etc!) is a fact of life, the Eyewitness Guide makes all that extremely straightforward so navigating your way round each section is a breeze.
Also, unlike a number of other guidebooks, aside from numerous photographs this guide provides immensely useful illustrations of key attractions. So you don't find yourself pouring over endless pages of text - as a guide it's therefore clear and very easy on the eye.
All in all, this is probably the guidebook I've found the easiest to use and would highly recommend it.