We really liked Saigon (apparently no-one calls it Ho Chi Minh City, its official name, except government officals and tourists)! Compared to Hanoi, it is a very cosmopolitan city and a bit easier to get around on foot (wide pavements, free of motos - what a luxury).
We had a rather exhausting 90 minutes in the searing heat looking for acceptable and within budget accommodation until we fortunately stumbled across a fabulous new little guesthouse down a side street. We visited the very interesting, but somber, Museum of War Remnants which was previously called a war crimes museum - its former title was perhaps a bit more instructive as to its contents, which were a very unpleasant reminder of the many landmines dropped on vietnam and its neighbours which continue to kill and maim, as well as the terrible consequences of the use of Agent Orange and some disturbing photography of scenes from the War.
On a cheerier note, we had the best, and most expensive, coffee and cake at Highlands Cafe - it was like being back in San Francisco or London at a good coffee shop.
Our day trip to the Mekong River was a pleasant day out (if a little bit touristy) and was slightly enhanced or ruined, depending on how you look at it, by the truly awful "äuthentic" Vietnamese singing and dancing that they insisted on subjecting us to after lunch.