Would you mind posting the actual makes/model numbers of all equipment involved? This way we make certain no options/alternatives are missed.
That said, you should avoid running audio to the HDTV and back out to the receiver if at all possible. Normally some amount of throttling will be present in content played back this way w/ most systems. IOW, you won't see much if any DD5.1 this way, let alone what you could get out of a blu ray player with expanded audio tracks. (Is your system 5.1 speakers/sub or 7.1, btw?)
Here are some connection options based on the info you have provided (knowing the actual model numbers can confirm this though).
#1 (Status quo)
#2 (HDMI direct to HDTV; separate audio to receiver)
DTV receiver (HDMI out) ---> (HDMI in) HDTV
"' "" (digital coaxial out) ---> (digital coaxial in) Denon receiver
BD player (HDMI out) ---> (HDMI in) HDTV
"" "" (digital coaxial out) ---> (digital coaxial in) Denon
#1 obviously gives you lesser video, but the full monty w/ surround sound
#2 maximizes your bang for your buck w/ the HDTV, and should give you the full surround minus anything that involves wideband codecs on the Blu Ray player (e.g. Dolby True HD, dts-HD, etc.).
I will try and word this as short as I can. I have 2 devices (bluray and DTV satelite receiver) I. I have always run them both HDMI to a Denon receiver , then the Denon receiver to tv again via HDMI. For kicks I bypassed the Denon receiver and went HDMI directly to the TV from both devices . Amazing improvement. The picture is so much improved. So... I am leaving it this way for video purpose, that is priority for me over the audio. Now for my question on the audio. Basically which method would be better? 1) The tv has an optical out to which I can send the audio signals to the Denon audio receiver. But its going into the tv via hdmi then out of the tv via optical or 2) Both the bluray and the satelite receiver have a digital audio coax out and the Denon receiver has 2 digital audio coax inputs. Is it better to go directly to the Denon audio receiver from each device. Or better to go the hdmi to tv then tv to optical out to the Denon receiver? I'm assuming their would be degradation going though a device like a tv instead of going direct from each device but would like an expert opinion. Thank you.