If there was but one thing you could have with you while traveling abroad, it would be a guidebook. Sure, money and your passport are important too. But does your passport have a map of all the metro stations? Does your money know the hours of operation of all the tourist spots in the city? Nope. They don't. And guess what, if your passport and money get lost or stolen, a guidebook will tell you what to do!
When I look back at all the traveling I did, I can't imagine how I ever would have gotten around without a guidebook. It's like imagining how people researched term papers without the Internet. Yeah it can be done, but why start a fire with sticks when you've got a match? When I told my cousin that I went abroad without first getting a guidebook, she instructed me to stay in my room while help was on the way. A week later two guidebooks arrived in the mail.
It's a good thing my cousin rushed me those guidebooks. It made me realize how utterly vital they are for smooth planning and traveling. Technically you could stop at tourist centers in each city you visit for information and maps about where to go, what to see, when sites open, etc., but again, why create work for yourself? Guidebooks allow you to look ahead before your trip so you can make a game plan, but they also help you to stay on your toes when you're hit with unexpected obstacles, such as sites closed for restoration or different holiday schedules.
My personal favorite guidebook is Rick Steves. Rick has practically become a member of the family, and you'll often hear us saying, "What would Rick do?" I even trained my friends to turn to Rick in their times of need. When it doubt, whip Rick out (I just made that up, but it's catchy, right? It's also true). He is the Bible of travel. My cousin may also have dedicated a photo album to him... might have happened.
Rick sets up each book with background history about the place you're visiting, important information - such as the European equivalent of 911 (it's 112, by the way) - and some fast facts. Next, he covers lodging, transportation, and food. He then separates the city (or country) into sections so it's easy to plan your trip geographically and also in order of importance, ensuring you don't miss anything. Each section provides a map already labeled with the routes and sites you'll be visiting. Rick often writes his own walking tour too (some are even available as free podcasts on iTunes), so you won't need the audio guide at the site. And if the site doesn't have any sort of guidance, you can wow everyone with your superior knowledge of what the heck they're looking at. Best of all, Rick lets you in on all the tricks of travel, like the best way to beat crowds, how to avoid scams, and when sites offer a discount (hint: go after 3pm).
While we were abroad, we spent every night pouring over Rick's books to determine what metro lines we wanted, what stops we'd need, what times the sites open, the best times to go, etc. Having a plan made our next day out hassle free and easy-going. We also took Rick with us so we could refer to his maps while we walked and read his notes about the sites/monuments/artwork we were seeing. Carrying Rick around also allows you to bond with fellow tourists. If you see anyone else with Rick, you're automatically friends.
The one downside to Rick is that his target audience can skew towards a specific niche: adult Americans traveling to Europe. He writes almost exclusively for Americans, and his books are only available here in the States. They also only cover Europe, so if you're traveling to Brazil, Rick can't help you. If you are in Europe, though, Rick's your guy. If you're not American, you'd probably do best to find the Rick of your country, but certainly the information is valid for anyone - maps are maps, and facts are facts after all. Rick's also not heavy on hostels and fast food, so students might be a bit put off. I chose to just ignore his lodging suggestions and use the tourist site info, which is the most valuable part of any guidebook anyway.
But if you want a guidebook with a bit more broad appeal, Lonely Planet is also a fantastic resource. If you go with one of their guidebooks that includes more than just the cities you're visiting, though, I warn that you may feel overwhelmed. While Rick only focuses on popular destinations within a country, Lonely Planet includes everything... and I mean everything. It can feel like traveling with a phonebook at times. However, their pocket and city guides are much more focused and less cumbersome. Lonely Planet also has guidebooks for the entire planet (duh), not just Europe, so they're a solid choice when Rick can't help you. Rick and Lonely Planet are about the same in price, too, so it comes down to preference.
One last note: always make sure you're using an updated guidebook. You may not notice many changes between 2010 and 2011 editions, but I certainly wouldn't advise going abroad in 2011 with a guidebook from 2006. You're asking for trouble. Hours of operation may change, renovations could cause shifts in what exhibits are open to the public, and new construction projects may be completed, meaning there's more for you to see! Getting the most up-to-date guidebook available ensures getting the most bang for your buck.
Regardless of what you go with - lord knows there are many more choices than just these two - just be sure to have a guidebook with you. I'd even suggest downloading some travel or city apps onto your smartphone if you're traveling with one. I promise you'll never curse the extra space a guidebook takes in your bag. I also challenge any of you to come back with it in pristine condition. It's impossible. You'll refer to it too much. ;-)