Thank you so much for your help! I ended up getting a smaller Antennacraft U4000. I'm very happy to report that we're easily picking up most of the local stations, including two Canadian TV stations, even CBLFT, which is pretty far down the TV Fool report list (53.6 mi, -68.7 or -92.9 dB depending whether it's Ch 25 or 24 DT?). As you said, since some of the signals are separated by about 90 degrees, it looks like we need at least two different orientations of the antenna to get all the channels. We're planning to move the antenna into our attic, where it would be very difficult to rotate it. Could you please let me know if it makes sense to get a second U4000 and orient it 90 degrees with respect to the first, connecting both with a splitter? One U4000 could be on the north side of the attic facing northwest and the other could be on the south side facing southwest. If this makes sense, how far apart should the antennas be? I may not have room to stack the antennas vertically, does the minimum horizontal separation differ from the minimum vertical separation? The advantage of two antennas is that I wouldn't have to worry about repositioning them or reprogramming my tv tuner each time I reorient the antenna.
The Antennacraft support team warned me that adding a second antenna would cause a signal loss of about 5 to 7 dB due to insertion loss in coupling the antennas into a single cable through a splitter. Although it would be fairly cumbersome to use, I guess I could run two cables, one from each antenna to the tv and connect one at a time to the tv? So would I be better off getting a motorized rotator, as you suggested initially, to reposition a single antenna in the attic for different channels? I would expect the signal strength to be better in the attic than at the ceiling inside the house, where it is now.
On another note, I can't get WKBW-DT Ch 38 (7.1) ABC even though the signal should be pretty strong. Can tall trees completely block signal if they're directly in line of sight with the transmitter? The other problem is that CBLT Ch 5 reception can be spotty.
Thanks again for your help,