I spent 5 weeks in Vietnam in early 2004 as part of a 3.5 month trip around South-East Asia. I rate Vietnam as possibly the most photogenic country I've visited - especially the people.
The highlight for me was the time I spent in and around Sapa - a small town in the far north of Vietnam not all that far fromthe Chinese border. The hills around Sapa are home to many ethnic minorities like the Hmong and the Z'ea, each with their own distinctive language, cultural dress and physical characteristics that separates them from the majority Vietnamese. I found it especially interesting that the languages of different minority peoples were quite different from one another, and the language of one minority would be unintelligible to another minority who just lived in the next valley over.
Other highlights of Vietnam:
Ho Chi Minh City (or Saigon): Plenty to do in and around here, and probably the prettiest and cleanest of the larger cities in all of South-East Asia.
Dalat: Small town in the Central Highlands with good walks and waterfalls nearby.
Nha Trang: A bit touristic, but sometimes touristic can be fun! Vietnam's premier beachside party town, diving can be arranged fromhere too. Be sure to join in the evening antics at the Nha Trang Sailing Club - just don't have too much planned the next day!!
Hoi An: Cute little town, good for mega-cheap imitation clothes tailor-made to your personal measurements (think Cashmere silk suit for US$30). Getting a motorbike from here and riding a couple of hours into the countryside to some old temple ruins was an interesting ride through Vietnamese rural life which I thought was even more interesting than the temple ruins we ended up at!
Oh, and if you're into photography be sure to visit Long Thanh's gallery in Nha Trang . Although you can see a small selection of his worksat the Nha Trang Sailing club, his gallery is amazing. Vietnamese life like you never saw it.