Try the Hilton on Wireless Road, it's cross-town from the River (east) but within walking distance to most attractions. Tip the bellman, and ask questions.

Also, if your interested in quality medical care, you can get an excellent executive physical at the Bumrungrad Hospital. It's like the Mayo clinic of the far east with discount pricing

Bumrungrad International Hospital | World-class Bangkok Hospital in Thailand for Medical Tourism

I got the full meal deal on a layover for about $400 and flex spending paid.
Bumrungrad International: Check-Up package comparison table - Health Screening Center

You can make an appointment online, and the care was first rate. Either way, knowing where a hospital is in a far off land can never hurt.