40 meters doesn't cover much of the CONUS these July evenings:
It's kind of noisy too, mostly from lightning. PSK31 can slice through the noise though, and 40m gives good Gulf, Florida, and Bahamas coverage.
Meanwhile, 20 meters is a badly fading long-range zoo:
Kind of exciting, but also kind of a crap shoot for where you reach. LOTS of traffic on 20m, the antennas aren't too big, and it's probably the single most-used ham band. West Africa is even a possibility – hey Cape Verde Islands, got any storms brewing up for us this week? Maybe I'll start targeting calls there this weekend.
But 30 meters is juuuust right to cover the CONUS and mostly keep things there.
Had a solid contact out to Colorado this evening, but beyond that there was not a lot of traffic. That's a shame, because 30m really is the Goldilocks band for CW and digital modes: it's both stable and gives good coverage of likely places. If you don't have an antenna sized for it, a 40m antenna readily tunes to this band. It is a pretty user-friendly band with good propagation properties, even if it's restricted to CW and digital modes only.
BTW, simulations courtesy of VOACAP.com