Buzzard - Saphan Khwai is now all karaoke bars except for Be High with a handful of gogo boys. I made a "research visit" half a year ago and blogged about it
here.
Kaojai - I have the same observation about trends. The gogo boys are getting older (and still in the business) and looks-wise, more and more like street toughs. Service quality after being off'd has been on the decline for years. Yet bar prices and expectations of tip quantum have remorselessly increased.
Where in previous visits to Bangkok, I used to visit at least one gogo bar a night (two bars if the night before I didn't visit), in recent years, I have been stepping into the Soi Pratuchai area maybe just once in 4 nights. The last visit, I didn't off a gogo boy at all - some kind of record for me.
Instead, I have been increasing my visits to massage places. Sure, they're hit and miss too, but I reckon that even if things don't turn out fantastic in a massage, they don't get as dreadful as a bad bar experience. At least I don't hassled by mamasans or threatened by the boys in my own room for tipping less than 2000 baht after 45 minutes of non-performance.