We were in Vietnam in December and have personal experience with some of the places you mentioned. I definitely agree with La Siesta Classic Ma May. Great location in the Old Quarter, excellent breakfast buffet, and helpful and lovely staff. If you'd like to explore the Vietnamese coffee culture in Hanoi I would recommend two other places in addition to your egg coffee class: Cafe Giang (where the egg coffee was invented: http://www.giangcafehanoi.com/) and C.O.C. Legacy Coffee https://cocsaigon.vn/search, where we learned so much about the various coffee growing regions of Vietnam and tasted various coffees. Both of these places are within a couple of blocks from La Siesta Classic Ma May. We also ate at Bun Cha Huong Lien or as they call it over there "Obama". Is it touristy? Absolutely! And it's probably not the best bun cha in Hanoi but it was cool to see where President Obama and Anthony Bourdain ate (tip: go upstairs for more seating and to see the actual table where they ate). Ha Long Bay: we did the overnight Ha Long Bay cruise on the Dragon Legend and we liked it. The food was great, and I think the excursions are going to be pretty much the same regardless of which cruise you take (the cave and the fishing village). If you decide to do Saigon, we LOVED the Hotel Central Riverside. Have a great trip!