Yes, you should bring guidebooks with you. More specifically, you should bring Lonely Planet country guidebooks with you, and supplement them with the fantastic resources available for free at Wikivoyage. But don't buy the paper copies; they weigh a lot, and you're only going to be using a few pages at a time.
Instead, buy digital PDF editions of Lonely Planet guides through their online store. It's often cheaper than buying the print edition, and though you may feel that the prices are steep when you're on a limited budget, it's like having a local friend in every new place you go.
Now, of course, you'll want to carry useful maps and information with you while you're out and about exploring, but carrying your computer or tablet would be ridiculous and cumbersome. This is easily remedied.
Many smartphones can read PDF files, so you could just copy the file to your phone, and read it there. But that's not easy to do, and often the readers are quite slow and difficult to use. Remember, you only need a few pages out of each book.
Instead, do this: use the camera on your cell phone (or your digital camera) to take a picture of your computer screen displaying the information you want to carry with you. I've used this method many times while traveling to "print" information, even hotel reservations and train tickets! It's one of those things that seems obvious in retrospect, but never occurred to me to do until I saw someone else doing it.
Likewise, if you are in an unfamiliar town and see a big, public map, take a picture of it. The streets that you'll get lost on are rarely the same ones that have maps handy!
Why Lonely Planet?
When I first started planning trips, to Europe, I would buy loads of guide books, from Rick Steves, Fodor's, Michelin, and everyone else professing to be an "expert" on Europe. And I'm sure that some of those guides -- the Michelin in particular -- are useful to a certain variety of traveler, but the Lonely Planet never hit a wrong note. Their mainline country-level guide series always seem to have the right amount of detail, and I've never been disappointed by their hotel or restaurant recommendations. (I will leave aside one glaring error in the location of a London restaurant called "Café in the Crypt," to be charitable).
These days, Wikivoyage can fill in the blanks and update what Lonely Planet can't, but too often Wikitravel is written by amateurs, or overtaken by local commercial interests; it can have big black holes. (The up side, of course, is that it's easy to help improve the site).
What really convinced me of Lonely Planet's superiority, though, was meeting one of the authors. He was an American who spoke fluent Mandarin, and knew Singapore inside and out. We were both staying at the best hostel and tour company in Singapore, the Betel Box. Shortly thereafter, it would go from zero recognition to the top listing in the new edition of Lonely Planet Singapore.
Lonely Planet's always been honest, not too serious, and full of travelers' tales. Their history and culture sections are top-notch, too. I can only hope that they don't lose this spirit under more corporate ownership, but there are worse masters than the BBC.