I’ve never been to Laos and Cambodia but I spent 2 week in Vietnam last month. May be experience of mine is helpful for you.
I stayed at Metropol Hotel, right in the heart of Hanoi’s Old Quarters. Anything you can buy in Vietnam, you can buy it in the Old Quarters. The room was nice and staffs were helpful. You can ask them anything (in English), place to eat, to shop, to have a massage. They will give you a map, show you the way or call you a taxi. They helped me to make a reservation at SF Spa. I had a wonderful Vietnamese traditional massage there. You may never heard about it but I must say it’s a can’t-miss-thing in Hanoi. You won’t have a chance when you come back. Here’s website I got from the receptionist in case I want to comeback.
http://www.tripadvisor.com/Attractio...Spa-Hanoi.html

I stayed there for a week, walking around to taste street food. No doubt, ‘pho’ was outstanding. ‘Banh cuon’, ‘bun cha’, ‘bun rieu’ were also wonderful. My 7 days was not enough to get them all. But be careful while trekking around. The streets were always crowded, you might be hit by a scooter anytime. You should have a guide to help you pass the road. And remember, always have a map and hotel’s card whenener go out.

I made a tour to Ninhbinh, too. Yes, Tamcoc was splendid, just like a heaven. But my local guide said the water will be bluer in July. If your plan is at that time, you can see lotus bloom everywhere. We spent 3 nights in Ninhbinh and tasted fried rice with goat meat. But it was a kinda sleepy town, only good for my age (60s), not the young couples.

We came back to Hanoi and spent 3 more days before fly back. That was an unforgetable trip and I wish to comeback for a more long term vacation. Hope to see you there.

We're going to Vietnam for 4 weeks in September.
My tour guides, who offer unbeatable and reliable vfm are called Crellston & thursdaysd.