Vietnam forum

We have 16 nights/15 days to visit Vietnam, arriving Feb. 15, 2011.
I've been doing a lot of research, and of course we can't do everything we would like, so I've tried to pick out a variety of experiences. Just wanted to run this proposed itinerary by you, and see if it's realistic, or too totally crazy... We are used to cramming a lot into our journeys, and like to see the countryside and local people, so don't mind a few fairly long travel days.

Day 1, (Feb. 16th), land in HCMC at night, stay in quiet hotel near airport to catch up on lost sleep
Day 2, travel to Dalat, spend two nights there. We won't be used to the heat and humidity of HCMC, so thought it would be more pleasant to be in the mountains where we could walk around for a day and relax. Also, we would need some time to arrange for a car and driver for the Central Highlands journey
Day 4, leave early for Buon Ma Thuot , spend one night there
Day 5, travel to Kon Tum , spend the night there
Day 6, Kon Tum to Quang Ngai (My Lai), then on to Hoi An (end of car trip), spend three nights there. (side trip to My Son, spend time at a beach)
Day 9, travel to Hue by train or private car, spend two nights there
Day 11, fly to Hanoi, spend three nights there. Take a day trip to Halong Bay. (We can't afford the luxury boats, and if it's raining a day there should be enough).
Day 14, (March 1st), fly to HCMC, stay three nights. Day trip from there to Mekong Delta, maybe Cu Chi tunnels; our flight to Hong Kong leaves at 6:00 AM on Day 17 (March 4th).

I heard that the Ho Chi Minh Trail from Dalat to Buon Ma Thuot used to be an awful road, but is now accessible in a 4 wheel drive vehicle. Do you know if that is the case? We don't want to travel by motorcycle. Frommers also recommended the above route through the highlands.

I guess the first challenge will be making sure we can actually get to Dalat on our first day in the country; I think we'd prefer to go by car and driver if we could be sure that the driver was going to be responsible and not drive like a maniac. That would let us stop to take photos and make a few diversions to waterfalls, etc. But I also read that the Mai Linh bus was OK, although it might be hard to get to on time from the airport. There doesn't seem to be a train. Any thoughts on this?