What is your favorite travel guide?

When I first starting traveling on my own, I bought my first travel guide. It is a 'Let's Go Spain' and honestly it is so beat up, ragged and over-used, but I cannot imagine throwing it away. I used it for a whole year to get around Spain and I literally brought it with me everywhere. Of course when I bought the 'Lets Go' version, I did it specifically because it had a plethora of information about hostels and low budget accommodations.

Now that I am considerably older and hostels don't hold the same place in my heart as they once did (perhaps it is the fact that you have to sleep in the same room as 12 strangers), I tend to stay away from the 'Lets Go' Travel guides. Since most travelers purchase books to read up on their destinations I am curious to learn, what is your favorite travel guide?

Here is the quick synopsis of some of the most popular versions:

Lets Go: A great option for those on a tight budget. I love the options they give because they find places at a great price that do not appear to be budget lodgings. Plus, they take into account younger travelers and their needs/wants, so this book always includes the best bars, trendy restaurants and other pertinent tips.

2. Frommers: Wonderful for travelers who are looking for mid to high priced accommodation options. Truth be told, this is now my favorite of all travel guides. I feel like their strength lies in describing a city before you arrive. They give a fair account of what to expect and especially the 'must-do's' that the region.

3. Eyewitness Travel Guides: I know so many people that swear by this book, because of the vivid pictures and maps included. I do admit that this guide includes more visual material than any other, but I think there is a big lack of content. I never find these books very helpful once you get to the location, plus I find the layout very confusing.

4. National Geographic Traveler: Obviously the photography in these guides are stunning, so be aware you experience might not be quite as beautiful. I love this guide because of the historical references it includes. These books tend to be a bit more expensive, but well worth it for a genuine understanding of the region in which you are traveling.

So what is your favorite travel guide?