Most common listening volume level for me is around 80 - 85db at my seated position, which is the center of a triangle with both speakers about 10 feet in front of me, and 6 feet to either side of me (angled slightly towards my position, of course). My ears at the seated position are also probably about six inches higher off the floor than the top of the speakers.
I find that this volume level equates to about 1 watt of output (based on the reading from my in-line analog Power Meter)... doing the traditional "1 kHz tone at 1 meter from the speaker face" on my Sansui SP-5500 speakers I get a reading of about 92 db on the db meter (official sensitivity rating of the SP-5500 is 98db; I have done some modifications to the speakers however, which may have affected that number)... I'm assuming the "at seated position" db level is lower due to the distance from the speakers and the fact that my listening room is fairly large (18 ft X 32 ft) and perhaps some sound absorbtion by the furniture in the room..?