We stayed at the Park Hyatt in April, just beautiful. We had 'come and go' travel arrange our transfers,visas and tour to Mekong Delta which is stunning and so worth visiting. I found them on Tripadvisor. We did the homestay in Ben Tre (Mekong) and the house is just lovely and chilled out place to visit. http://comeandgovietnam.com/
We then went to Danang and Hoi An, but have heard Nha Trang is excellent too.
Food is so good!
We used Vietnam Airlines and Jetstar for internal flights, I must say Vietnam Airlines better with their timing, Jetstar we had a 2hr delay, luckily I knew this happens and left plenty of time for our connection to Dubai.
edited by TimTam on 21/06/2012 (because I can't spell!)
<em>edited by TimTam on 21/06/2012</em>
Saigon - Cu Chi tunnel tour via riverboat - www.saigonriverexpress.com
Saigon - motorcycle tour of city, also motorcycle tours out to countryside -
www.vietnamvespaadventures.com
Saigon - motorcycle tours with Vietnamese girls driving, city tours and "foodie" tour (didn't do that one, was fully booked, but people raved about it - www.xotours.vn
Saigon - great hotel and location - Park Hyatt Saigon
Hanoi - plan carefully if you want to see "Uncle Ho" in his mausoleum, it's closed certain days
Hanoi - great hotel and location - Sofitel Legend Metropole
edited to add: got great rate for Sofitel Legend Metropole on www.agoda.com
and be very, very careful not to schedule too tightly when traveling between cities on Vietnam Airlines. They have a nasty habit of changing flight times and not notifying you.
<em>edited by adpat on 20/06/2012</em>