Running iStumbler (98) I can see that even in the same room as my base station, signal strength for my networks is pretty low. 65% for 2.4GHz and 59% for 5GHz. I'm about 10 feet away from the base station (MBP about 2 feet lower than base)

And back in the same room I was initially testing in, which puts the computer maybe 15 feet away from the base station, but with two sections of wall between, signal strength is at 58% and 43%. The 5GHz strength is actually lower than the signal strength of some neighbor's 2.4GHz signal. I have a few other neighborhood networks ranging from 40% to 47% at 2.4GHz from this location.