When to use rec 709 color space? both web and hdtv distribution?

[mannfilm]

A short Film will be streamed or downloaded to computers and media streamers for playback on both computer monitors and HDTV's.

I understand that HDTV playback requires Rec 709 colorspace. But the Rec 709 looks flat and unsaturated on a computer monitor.

Downlaoding iTunes, the same  movie or music video  looks great on both monitors and HDTV's so duel playback is possible. This there is some type of trick to making Rec 709 look good on a computer monitor? Or am I missing something? 

[mannfilm]

Answer myself after research. Always use Rec 709. Log looks terrible on HDTV's and today, everyone is streaming to HDTV's. The new Final cut X 1.2 automatically does everything in Rec 709. The new mac's all have HDMI ouput which is Rec 709 native.