2 weeks Vietnam, 1 week Cambodia

It's realistic though a bit rushed, especially the one week in Cambodia. Do you plan to fly to Siem Reap from HCMC? If you're traveling by land from HCMC you'll end up in Phnom Penh. For photography I recommend you do the Mekong Delta, it's one of the most photogenic parts of the world, and skip HCMC which is probably the least photogenic. You can take the river boat up to Phnom Penh from Chau Doc in the Mekong Delta. Also if you've been to Hanoi already HCMC will not give you anything more. You could spend 8-9 days in North and Central Vietnam, fly to HCMC, go straight to the Delta, make your way through the delta in 3-4 days then take the riverboat and do Phnom Penh + Siem Reap for your week in Cambodia. This is a very busy itinerary for three weeks though, probably too rushed for some.

Agree with the post above - It is doable!

Yes, seemed a bit rushed to me too...perhaps leave out either Hue or Hoi An? I want to have free time to just walk the streets and enjoy a cold beer or two and the street food everywhere we travel.

So skip Hue!

I need to figure out the Mekong Delta, most I've read says its a big tourist trap!

So skip Hue!

No, skip Hoi An, which used to be a charming small town, but now is totally over run by tourists. Hue has some wonderful sights.

Or skip central Vietnam altogether and just do the north and the south of Vietnam.

I need to figure out the Mekong Delta, most I've read says its a big tourist trap!

There are millions of Vietnamese people who call the Mekong Delta home, so no it's not a tourist trap. It's just if you join a tour group that's going to go through the Mekong Delta in 2 days/1 night, of course it's going to seem touristy. Those groups generally treat tourists as cash cows, and frequently stop for "shopping" opportunities.

With a week in Cambodia, you're probably restricted to just Siem Reap/Angkor Wat and one other place. For most people that would be Phnom Pehn. If you don't want to fly from HCMC, you can get there by using a speedboat that goes every day from Chau Doc in the Mekong delta.

Can anyone suggest a rough itinerary for Mekong Delta? I have no ideas about which towns are worth visiting (and how many nights should I stay there)

I went to about 4-5 little cities and I found there were all different and worth visiting. This topic has been discussed a lot here, so if you search the forum you'll find a lot of discussion on which specific ones to go to. I spent a week there and wished I had at least another week, it seemed so little. As for being touristy, since I was traveling independently my problem was exactly the opposite, I wish it had been more touristy so it would have been easier to get around. It wasn't it was as pure Vietnam as it gets.

2 weeks in Vietnam are not enough unless you run from one place to another. I WTRONGLY recommend that you visit the fanatstic North (Hnaoi, Halong, the mountains (Sapa.Bac Ha) and end your tour of the North in the marvelous "Halong Bay on Land" of Ninh Binh-Tam Coc (for 2 days). End of the last day, you take the night train Ninh Binh-HUE and visit Hue for 2 days. Then CAR fo a superb day Hue-Lang Co Laguna-Pass of the Clouds-Danang-Cham Museum-Marble Mountain-Hoi an, which is indeed touristy, but for an excellent reason : it is extremely charming and historically interesting. Then, you take a DIRECT flight Danang-Siem Reap for at least 3 days amid the Tempels of Angkor. The South is nice, but less interesting.