Hi There
I did this trip 4 years ago (my last time abroad pre Covid) and it was amazing (in Oct/Nov)
I had a large case for holiday and flight bag which i used for the over night stay on the boat in Halong bay (which was amazing) You have your own room and shower and it reminded me of the film "Death on the Nile" - there wa a cooking class and rememebr getting up at 6am for an exercise class
Hoi An was fantastic and a lot of people got clothing made there, go in at night when its all lit up - really special
I didnt do the tunnels as I had a cold and had a lazy day by the pool which was lovely and 4 of us went and had pizza for a change
I lived in shorts and T shirts, and light and airy clothing / floaty skirts and dresses - If you are going to Cambodia you need to keep knees and shoulders covered as its a religious site (the day trip on the Mekong was amazing and Cambodia was magical)
I had a waterproof jacket and only wore it once in Cambodia, it poured down the morning we got up early to see sunrise at Ankor Watt, I only wore my cardigan on planes!!
I paid for most things in Dollars - the markets are great and remember to barter!
The hotels were lovely, the food was good and Im fussy - I came back with lots of money too as so many meals were included
You can go off and explore yourself as well as Tuk Tuks are so cheap - the only tour i didnt like was night tour in Phnom Penn as the food was awful but hopefully they changed the venue since then
You can easily see it by night in a Tuk Tuk which all wait outside hotels
The Tour manager recommends what to tip guide and driver and $$ were fine to use
Have a fab time! x