lilditty ... I use Comcast, but have no HD package, which is needed to get any HD through their boxes. You get the locals in HD by bypassing your set-top box and using your HD TV's QAM tuner, as already noted. I do this all the time.
The A/B switch looks like a 2-way splitter with slide switch built in ($5 online), and works well, except you have to get up and manually actuate it. So you first split the cable, put one part to the cable box and then to the switch, and the other directly to the switch, and the switch output goes to the TV (there may even be remote control versions of the coax A/B switch).
Absolutely agree about the Comcast Guide, and never use it on the TV. Their smartphone version is quite useable, however. TV Guide also has a good iOS version, as well as PC version, so you could try that.