Exotissimo Travel has a desk at the Hilton Hanoi Opera (1 Le Thanh Tong St.); they also offer tours in Thailand, Cambodia, Laos and Burma (Myanmar), with travel offices in the major cities of the countries covered. I was very pleased with the services provided, which include very knowledgeable local guides, and will use them for travel in Laos on my next trip. When in Hanoi, definitely consider a 2 to 3-day excursion to Sapa and Bac Ha, with a Saturday night departure from Hanoi by night train to see the Flower H'mong hill-tribes at the Bac Ha Sunday market (pictured).
