One of the things I’ve noticed is that HD makes absolutely no difference to the viewing habits of some of my friends. But when combined with a DVR, and when (re)broadcast sans commercials, some shows really shine.
For example, I was a few years too late to the “Arrested Development” party. It was a show that, when I lacked a DVR, I liked, but I never followed closely enough to care when it was eventually cancelled. Now, I find myself laughing hysterically whenever someone mentions Mr. F (which coincides with Charlize Theron’s appearance on the show as a developmentally challenged British woman — who everyone thinks is smart because she has an English accent). Now, it’s broadcast on HDNet, commercial-free every weekday.
I’ve found myself really enjoying “Star Trek: Enterprise” (also DVR’d five times a week) despite the craptacular theme song.
Scott Bakula’s Captain Archer is somewhere between Kirk and Picard, and while a lot of hardcore Trekkies seem to dislike the show, I kind of dig it.
Sex with Vulcans is also hotter in HD.
Some of the better episodes include Brent Spiner’s appearance as Dr. Arik Soong who attempts to raise genetically engineered human embryos (a.k.a Augments) who become “superhumans” capable of smacking around Klingons in hand-to-hand combat among other things, and an episode where a male crewmember finds himself pregnant after an encounter with an alien species. Oh, if only that had happened to Captain Kirk!
Yeah, but we he be smiling if every time he touched a blue woman, he got knocked up? I don’t think so!
Recently, I also found myself hooked “In Treatment” and the”John Adams” mini-series on HBO, and both shows were markedly better in HD with surround sound. The cinematography in “John Adams” was gorgeous, including some memorable scenes from his visit to France.
“In Treatment”, on the other hand, benefitted from HD in much more subtle ways. While each moment on film was not intended to be as awe-inspiring as a scene from “Curse of the Golden Flower”, this show has a quiet, understated charm to the way it is filmed, and it absolutely shines in HD.
HBO’s competitor, Showtime, also rocks the HD. Case in point, if you like “Dexter” from the re-airings on CBS sans some of the blood, gore, sex, ‘n cursing, I bet you’d like it even more in HD. Heck, all the CSI shows benefit from HD, so you can guess Dexter is also a bit more… visceral… when viewed in high-definition.
Perhaps another reason why I’ve become such a fan of TV shows that I might not have taken notice of before is because while my “old” HDTV was on the fritz, I could only watch DirecTV.
Powering up the Playstation 3, or attempting to watch over-the-air HD via my PowerMac G5 would cause the TV to go dead. I’m still waiting on a repair courtesy of my extended warranty coverage (thanks for nothing WarranTech / Repair Master). Now that I can savor movies on Blu-Ray again, I’m looking forward to curling up in a ball one day and just watching a pile of Blu-Ray discs I’ve got from Netflix.
Yum. 
P.S., The alternate ending for “I Am Legend” on Blu-Ray is waaaaaaaaaaaaaaay better than the original theatrical ending. Go see it NOW in HD.