Hanoi is THE town for sidewalk dining in my opinion. I suspect that people there don't do anything but ride motorbikes and eat delicious meals on the sidewalk. I'm so jealous that you're going there. There are many differences between northern and southern cuisine - pho is a great example. In the north they give you a bowl of soup - a perfectly balanced, delicious bowl of soup. In the South they give you a delicious bowl of soup plus a plate piled sky high with different herbs (basil, cilantro, mint, lime etc.) and you engage in some major self-garnishing. At first, being used to the southern way, I thought the northerners were crazy. What's pho without a squirt of lime juice? But now the northern style is my FAVORITE (Don't tell my relatives!) Not that I think you need a guide book, but if you're curious for some online recommendations, you can't go wrong with Reid on Travel: http://www.reidontravel.com/http://www.reidontravel.com/ This pho place Mr. Reid raves about in Hanoi was fantastic. My Vietnamese husband, who grew up eating pho every week, called the place "revelatory." He doesn't normally use words like that. So jealous, enjoy your trip!