My husband and I are planning a trip to Vietnam in late April, early May. I'd like some feedback on my planned itinerary to see if it's too ambitious.
Day 1- land in HCMC
Day2-HCMC
Day 3-HCMC
Day 4- Mekong Delta tour
Day 5- fly to Hoi An
Day 6- Hoi An
Day 7- Cham Islands
Day 8- Marble Mountain
Day 9- travel to Hue (by train?)
Day 10-Hue
Day 11- fly to Haiphong
Day 12- Bai Tu Long Bay tour
Day 13- bus to Hanoi
Day 14- Hanoi
Day 15- Hanoi
Day 16- Hanoi
Day 17- fly to Siem Riep
Day 18- Angkor Wat
Day 19- Angkor Wat
Day 20- fly home
I also wonder if it's necessary to make hotel reservations and arrangements for various tours before we arrive. I usually make hotel reservations only for the first few nights after arrival and the few nights before we return home so that I can have some flexibility about how long we spend in each location. I appreciate your feedback.

I think your itinerary is a little ambitious with a lot of moving around but entirely possible.

A few observations.

An overnight trip to the delta is not long but I guess you are going on an organised tour? The closest place worth seeing is around Ben Tre, small canals, rural industry, coconut farms/processing etc. An alternative would be Can Tho for the early morning market (5.30) at Cai Rang which would leave enough time to get to the airport for your flight north. It is a long trip for one day.

Hoi An does not have an airport so you would have to fly to Da Nang and get a bus or taxi to Hoi An.

I would not bother with an overnight trip to the Cham island. Stay in Hoi An and do a day trip but quite frankly IMO it would be a waste of your time as there is so much to see in Hoi An and Hue. In fact adding one of those days each to Hue and Hoi An would be much better.

You don't need a night in the Marble mountains as you can visit on the way to Da Nang airport by taxi ($50-60) inc. a couple of hours in the marble mountains. However that would mean not doing th train ride between Da Nang And Hue which is fun but you will see more by going over the Hai Van pass and stoping at the mountains.

Generally speaking it is easy to arrange hotels on arrival, which is what we tend to do, but as you are only staying 2-3 max in any one place, I would book in advance. Vietnamese taxi drivers are better then they were but explaining where you want to go can be "challenging" at times. Often as cheap and easier to ask your accomodation to pick up from airports.

Any hotel in Hanoi will organise tours for the next day to Halong without a problem but I think you would have to organise your BTL cruise from Haiphong in advance as you are not staying in Hanoi beforehand. Some more info and photos of our time in Vietnam our blog https://accidentalnomads.com/category/vietnam/

I wouldn't take tours in any of these places - unnecessary. But I would book hotels ahead, so you don't waste your precious time in these places looking for a place to stay.

Thanks for the input. I revised our itinerary a bit to include your suggestions. I am planning to drive from Hoi an to Hue with a stop in the Marble mountains. Is that feasible?

If you mean hire a car and driver to do this, then yes, it is feasible. If you are thinking of renting a car and driving yourselves, then no, it is not.

Yes it is feasible, indeed, recommended. Allow four hours inc. two exploring the marble mountains. Try to leave early to avoid the crowds and heat. Most hotels will arrange a car and driver for you. As mentioned in my previous post, expect to pay $50-60.

Thanks for the information. I think I'm ready to go!