We are a small group interested in visiting Siem Reap and Phnom Penh. We'll be traveling from Thailand across Cambodia and Vietnam and we're wondering whether this is safe to do. Is Cambodia okay to travel from city to city independently or do we need to do it with a tour? what are your thoughts?
basically same as you would do back home not another "safety concerns" thread...Common sense is all you need in Cambodia! don't flash cash, your bling-bling, or walk at night...basically same as you would do back home and you'll be fine. You won't even need to book with a local tour if you want to do Siem Reap or Phnom Penh, just hire a tuk tuk and tell him where you want to go and sit back and enjoy.
If you take a tour, they will plan for your vacation. For the trip to Thailand, Cambodia and Vietnam, you can book a tour of Vietnam tour booking.
Personally, if you have travel experience before, you can travel alone but if not, you should book tour to travel, the agency will make sure about your safe, itinerary and transfer as well for you. You can refer some reputable agencies like Asia Group Tour - guaranteed best rates for Halong bay cruises and Vietnam tours, Vietnam Group Tour