We are planning a trip to Ho Chi Min, Hanoi and Singapore. Has anyone any suggestions for accomodation in each of these cities. We have never been there and have no idea on location and close transport. We would appreciate any help we can get.

You'll need to give us a nightly budget in order for us to be of assistance.

Not knowing your own budget, I will offer you what we slected after doing our own research. We booked the Liberty Central in Saigon, which is brand new and will be opening any day now. For Hanoi, we chose the Hanoi Elegance 4. Both are centrally located, had good reviews and are very reasonably priced - around $50/night.

I would check on Tripadvisor. I always check the # of reviews, the number of contributions by the reviewers and the bad reviews. This has really worked for us and we are in SE Asia right now traveling for almost 3 months an mostly booking only 3 or 4 days ahead. We stayed at the Rising Dragon II in Hanoi and it was super for $40 a night. We could walk everywhere, it was very clean and the service was great.
All your needs can usually be met at the front desk of most decent hotels here. They will arrange your pickup, drivers you might need, taxis etc. It is a very service oriented system and they are willing to help you at the front desk. Now I would be a little more wary of using "travel agencies" but we have had excellent results so far from the hotels we have stayed at.

Thank you so much for all of your suggestions and prompt replies. I really appreciate it. I found on the web that the Hanoi Elegance 5 is about to open so I might try that one.
Has anyone any suggestions for Singapore?

The Intercontinental was very nice, and I really liked the location.
The YMCA at One Orchard road is a very nicely located budget hotel.

those hotels above are both in Singapore. The Spring Hotel in Saigon is a pleasant, very Vietnamese hotel in a great location.