What pitch attitudes are common during an emergency descent for an airliner?
My experience was on the Regional Jets but from sim training I recall that the pitch down once at Vmo with flight spoilers extended was somewhere around 10-15 deg.  The standard procedure for the CRJ was to declare &quot;emergency descent&quot;, slam the thrust levers to idle, flight spoilers fully out, dial the Autopilot altitude preselect to 10000 ft, select the Autopilot to Speed Mode, and dial the speed select to Vmo, and just let the airplane do its thing while the two of you went through the QRH.
You will get a small G reduction during the pushover, but the AP would pushover gently enough to avoid making people in the back float around.  If you push over manually, there is a risk of pushing too hard in the stress of the situation and banging heads against the ceiling in the back (it doesn't take much when you're going fast like that).
Any G reduction that occurs is only momentarily during the pushover.  Once up to speed you are back to 1 G more or less. The pitch attitude in the descent would be noticeable to a passenger looking out the window from the slanting horizon, but I don't think it would look like they were diving straight at the ground.  The scarier part would be the rumble from the spoilers being out, and the roar in the cabin from flying at Vmo.