All HD channels of star network, Colors HD and the two HBO HD channels. We are talking about 10-12 true 5.1 channels here and with the limited per day average viewing time available for common man these days, I believe thats more than sufficient options for 5.1 set up to be worth it.
Content type is personal preference.I stopped playing 5.1 through STB long back, reason is the annoying ads (did not subscribe to the ad-free channels separately). So for serious movie viewing it is always HTPC.
I never watch movies on TV ads are too annoying. Can download in full HD and watch at convenience.
For most general Ent and Sports Channels no true 5.1 sound available.
It'd be great to watch sports (esp football) in true 5.1. But no. Star Sports HD (both) are fake 5.1 as i read somewhere.