I've just used them on the back of this recommendation, and have been REALLY impressed so far. Have not travelled yet, but they were tremendously efficient in making the boking, replying to e-mails etc and a lot cheaper than booking directly with the hotel.
Starting either HCMC or Ha Noi the trip would be (assuming Ha Noi start)
Ha Noi >>(book your SaPa rail journey at the station YOURSELF before heading for HLB) >> Ha Long Bay >>(pre-book online with www.Tropical-Sails.com) >> Ha Noi >>rail>> Sa Pa >> rail >> Ha Noi >> rail sleeper >> Hue >> (either An Phu or Sinh bus) >> Hoi An >>(sleeper train from Da Nang booked in Hoi An) >> Nha Trang >> (either An Phu or Sinh bus) >> Da Lat >> (either An Phu or Sinh bus) >> Ho Chi Minh City.
Recommended accommodation:
Ha Noi
Asia Queen Hotel
16A2 Trung Yen Lane
Hoan Kiem Dist
Hanoi
SaPa
Baguette & Chocolat (just ask for directions)
Hue
Nguyen Tri Phuong Hotel
56 Nguyen Tri Phuong
Hue-Centre
Tel: 054-829-282
E-m: NguyenTriPhuong@yahoo.com
Hoi An
Nhi Nhi Hotel
60 Hung Vuong
Hoi An
Tel: 0510-916-718
E-m: vancamdn@yahoo.com, letannhinhiha@yahoo.com
Nha Trang
Da Lat
BA TU (Room 203 is best)
34-G1 Nguyen Thien Thuat
Nha Trang
Tel: 058-522-466
Mobile: 0905-369-867
Ho Chi Minh City
www.IndochineHotel.com
If you only have 2 weeks cut the northern section (Ha Noi) off at Hue at return back to Ha Noi.
Dreams Hotel
151 & 164 B Phan Dinh Phung
Da Lat
Tel: 063-833-748
E-m: dreams@hcm.vnn.vn
More info from: WomPom@WomPom.ca, too.
September is an interesting time to travel - you might want to skip Hoi An because of the weather (storms) only present in that part of the country.