I am planning on travelling to Vietnam and Cambodia in November with a friend of mine. We only have 7 days and was wondering if there were any suggestions as to what the "must see" places are in both of these countries. We would like to experience the culture, do some market shopping, sight-seeing and also include some time on the beach. Any suggestions would be welcome. Would it be a better experience to rather only visit one of these destinations instead of both?
Seven days and you want some time on the beach?
Saigon and around, through the Mekong Delta to Phu Quoc. Fly back to Saigon.
Try to do much more than this and you'll be rushing about seeing nothing but airports, train stattions...
As Wants2BeHappy says, with only one week you really want to stick to one geographical area, rather than trying to fit in 2 countries.
If you want beach time, you'll probably want to avoid northern and mid-Vietnam as it will be cooler and rainier in November (at other times of year I'd have suggested you base yourself around Hoi An/Hue for a week as that would give you a good mix of culture, history, siteseeing and beach). But because of the weather patterns in November, instead I'd suggest you pick either south Vietnam (as suggested in the post above) or base yourself in Cambodia (Angkor, then down to the coast via PP - there's some itinerary suggestions here https://www.travelfish.org/trip_planner/cambodia-one-week-trip)
Have a good trip
Vietnam; climate wise it is a great time to fly into Hanoi . . . but you won't really get beach time, you'd be able to hit up around Sapa for a couple nights, the city for a couple nights and a night or two on Ha Long Bay. If you were to go to Saigon I agree to head into Can Tho for a night or two . . but you may be better off just getting a round trip air ticket to Phu Quoc.
Cambodia . . . you'll probably get more history by just splitting your time between Siem Reap and Phnom Penh . . but if you want beach time you could always shave off a little time from both locations to take a bus to the south coast for two nights.
I have trouble thinking of any decent itinerary with only 1 week. Is it possible to get more time? The problem is that most of the "must see" locations in these countries are spread out and not the easiest to travel to quickly.
Best I can think of to meet all your criteria is to spend all your time in Cambodia. Fly into Siem Reap and see the temples and look around town. Then fly to Sihanoukville and from there can go to Koh Rong, Kampot, Kep or Koh Tonsay depending on which you find most interesting. Then take bus or fly to Phnom Penh to end trip. Will be a bit of a whirlwind trip but gives you a "must see" in the temples and also has the shopping, culture and beach time like you are looking for.