I would highly recommend Scenic USA which is an Australian company with branches in the US. It is mainly a river cruise on the Mekong which starts either in Hanoi or Siem Reap depending on the tour you choose. We did this tour in March a few years ago and it was absolutely fabulous. It was all inclusive. Once you paid for the tour, you didn’t have to open your wallet again. There were excursions in the morning and the afternoon all included and entertainment at night. Although the ship took 100 passengers, you were divided into 25 person groups with your own tour guide so it felt more akin to a RS tour in that respect. The ship was gorgeous, wonderful large cabins, great food, sights and experiences, staff. All that being said, it is unclear what the covid situation will be in that area early next year. You should also consider what the temps will be when you plan to go. It was pretty hot and humid when we went in March. Luckily there was a laundry on the ship so we could wash and dry (and press) our clothes as needed or your could pay to have your onboard butler do this for you (the one thing you would have to pay for if you chose to go that route). Also consider what their refund policy is should that tour not depart because of covid. I believe they were giving vouchers for last year’s canceled tours.