I just went through this agonizing decision myself a couple weeks ago.
Crutchfield has the 3806 on pre-order for $1300.
Crutchfield Denon AVR-3806
ibuyplasma.com has the 3805 for $755.
http://www.ibuyplasma.com/product/?05084
At that price difference The choice became easy for me. I went with the 3805.
HDMI and DVI are cool, but all my research has shown that good component cables will produce a picture equal to the digital inputs. Down the road as resolutions increase and as the digital interfaces are improved, digital video will be necessary, but by that time it will be time for a whole new receiver for most of us..
A downside is the 3805 does NOT come with the mic, so you will need to spend $50-$70 for that separately. The 3806 comes with the mic.
The 3805 remote is really cool, though I wish it would stay illuminated longer before it auto-turns off the back-light to save power. Maybe there is a setting to change that.
I hope my info is helpful. I'm really new at this so please forgive me if I overlooked something important.