Sanj, When I said IIM, I meant IIMA and that too its exec program. IIMA's exec program placements are top notch. Average salary is much higher than ISB. Apart from that, if you are a 30+ candidate, you will find most of the students there of your age range. Three people I know passed out from IIMA PGPX and following is what they are doing after 3 years of passing out:
1. CEO of a hotel chain
2. VP of sales in US for an Indian firm
3. Head of Integration practice of a large Indian IT company.
These are just three people whom I know. As my friends are added to my linkedin account, I am able to see the employment history and placements of most of the guys who are from IIMs and who studied with my friends. They are all top shot execs and are currently at very senior positions.
ISB has a varied crowd. Some of the guys I know went to ISB after 2-3 years of exp. In the end, it's all your preference. My preference is IIMs.