Follow-up task: Since we know we want to do this, I need to research each cruise line and select at least our prefered line. Once that's done, we can add the info to the "Top 20" page.
According to Cruise Critic:
- Itineraries are similar for all cruise lines
- Can be cruise-only or combined with land tours
- Most go between Hanoi and Ho Chi Minh City
- Some sights are available with cruise extensions
- Cruise advisor suggests first deciding budget and sites to narrow the possibilities
- Best time is November through February (rainy season is July through October though rain falls only for about 30 minutes)
- River is highest in September
- River port highlights: Hanoi, Siem Reap, Kampong Cham, Phnom Penh, Tan Chau, Vinh Hoa, Sa Dec, Cai Be, Ho Chi Minh City
- Dress for heat, be a smart eater and don't pet the monkeys
Here's a summary I put together comparing these cruise lines.