I’m not a fan of travel guides in general. I can’t get myself to spend $20 on a 100 page book about a destination I’ll visit, because I’d honestly never read it. It’s just far too organized for me. I prefer just to roam the city and get tips from the concierge, but one guide I’ve used all over the world is United’s Three Perfect Days. It is published in Hemispheres Magazine (the United in-flight magazine), and every month features a new destination.
They have an archive online where you can print out the articles for free, and I’ve used them for cities all over the world, and have always found them to be useful. While it’s no exact guide that will give you directions, it’s great to be able to go to the concierge at a hotel and say “I want to go here.”
If you’re interested, the archive is located here.