Sorry but even during covid thailand hasn‘t been like 30 years ago (when i first came) the whole society changed, the country is overdeveloped,no tourists during covid didn’t do anything for getting that old feeling back,you‘re wrong
Bangkok is fantastic. We love it. (Not for a living,but always everytime we’re in Asia) I think you‘re doing it right with 10 days,so you can move through the city slowly. Just make sure you‘re having a good hotel to rest inbetween,with a garden and a pool. Best near the river. If you like to historical sites, i‘d suggest you a daytrip from Bangkok to Ayutthaya!