I used to go to Bumrumgrad, but I switched to Samitivej in Thonglor. IMO, it's every bit as good and at least 25% cheaper. I got a complete work up last year and it saved me 10,000B over Bum. It's not as easy to get too though. It's not close to BTS. LINK:
http://www.samitivejhospitals.com/ho...vej-sukhumvit/