Volume seems too low

Fairly big room 18x40. Usually not real loud, but I do crank it from time to time. I just found it curious I have to dial it up so much to get semi-loud.

84 dB speaker sensitivity means they need higher power from your amp, thus you need the Volume Control up high to drive them. Look for a speaker with a sensitivity of about 90 dB and your amp will have an easier time driving them.
So as Elizabeth said, 2/3 up isn't surprising.
But IMO, you're pushing your amp pretty hard to fill that room.

Thanks for your help. Looking at speakers now. I will have to pay more attention to sensitivity. Thoughts on speakers? Devore?

amp should be plenty-nuf for your speakers. although your speakers are 8 ohm nominal, i'd recommend to try 4-ohm taps and see if you get them screamin' louder.
otherwise i'd check tubes and their bias(if ias taps are available)

Oh...such a sensitive topic :-)
You should look out for speakers that are at least 90+ DB sensitive. The more the better (and merrier).