Don't know what speakers you have, but....to give you an example, with an average 15 x 15 room with 9' ceiling, and speakers with average spl of 89-90spl, your description of the volume sounds about right. I had a Yamaha HTR 5250 (100 watts-circa 2001) which was one of the last analog volume controlled AVRs. It was comfortably loud at about 10 o'clock. But, it was not much louder at 12 o'clock and distorted above 2 o'clock.By comparison, my newer Yamaha, rated at 100 watts is generally at -20db for average-slightly loud levels. Those old units were biased with much of the power up front. I suspect they did that for two reasons 1. it gave the perception of power and helped sell units and 2. It made sense so that you did not have to spend time turning the units up to a decent level. I think your Denon is fine, remembering you need to double the power of a receiver to get about a 10% volume increase....just the way it is...
The second issue is hearing dialog....I feel your pain. This has been my complaint since the era of high dynamic range began. With Blue Ray, DTS and even Dolby digital, the range has increased to the point where, in a lot of cases, to hear dialog, you have to endure very loud special effects. I have never found an answer for that. Your receiver will allow you to reduce the dynamic range. Of course that defeats the intent of the film maker to shake you out of your seat with the effects....just the way it is....and thats reality. Think about it, if you were standing by the tracks talking to a friend when a train came by, you would not expect to hear your friend, but thats what we are asking the sound engineers to do.