To complete a few promos and trigger others, I need a night at an IHG hotel.
My best bet for that stay would be during a layover in BKK. Arriving around 7 PM (with fast pass), flying out 9:20 AM the next day (international departure, no fast pass but *G).
Would the Holiday Inn Express Bangkok Soi Soonvijai be a somewhat reasonable option transportation-wise? Or maybe some other IHG property?
I realize this is not the IHG subforum. But I think the biggest expertise on transportation around BKK is here. If you're all saying "this is a really bad idea", I might push that IHG stay to another date and stay at a BKK airport hotel instead

I did something similar earlier in the year, although not entirely for the points but more from a practical stand point. Landed into BKK at around 01.30 hrs and so checked into the Holiday Inn Express Bangkok Soi Soonvijai. Later in the day, shifted to the Intercontinental. The ride from the Holiday Inn Express Bangkok to the Intercontinental took about 35 mins in a taxi around 11 in the morning.