THE NATIONAL PARKS: AMERICA'S BEST IDEA. 8 tonight through Friday, Channel 12.

LET ME just say I'm a sucker for national parks.

Over the past 20 years, my family's camped on both rims of the Grand Canyon, at Acadia in Maine and Mammoth Cave in Kentucky. We've spent a couple of nights in a cabin at Badlands - our storm-soaked tent pitched outside to dry - and we've spent days absorbing the beauty of northern California's Yosemite.

Over the years, I've visited a couple of dozen more national parks and historic sites, and Yellowstone remains high on my bucket list.

So while I may not be as sure as Ken Burns is that the national parks are "America's best idea," I wouldn't put them far behind the Bill of Rights and blue jeans.

I should, I'd supposed, be the perfect audience for the filmmaker's latest epic for PBS, "The National Parks: America's Best Idea." And yet, having made it through just six hours of the 12 scheduled to air next week, beginning Sunday, I can say only that I tried - and ultimately failed - to love it.

Oh, it's pretty, all right. If you happen to have one of those flat-screen TVs that takes up a wall, you could run the first installment on a continuous loop, the way appliance stores seem to do with Discovery Channel nature shows to show off high-def sets. But unless you're immensely interested in every last detail about the development of the national park system from 1851 to 1980 - or want to wind down before bedtime - you might be tempted to hit the mute button now and then.

Burns made his reputation in part for being able to take subjects like "The Civil War" that didn't have many moving parts available, and finding ways to keep them moving. That's hardly necessary in "National Parks," where, when the black-and-white still photos pale, there's always a beauty shot of Yosemite or Yellowstone that can be cut in.

But the real strength of Burns' best work is in the way he pairs pictures and people, as he did, for instance, in his 2007 series "The War," where he assembled a cast of true characters whose stories carried us through 14 hours that might otherwise have been grim indeed. (I took all seven episodes with me on vacation that year, in preparation for my review, and looked forward to each new installment.)

The parks opus could have used more of that kind of storytelling. Of the talking heads in the series' first half, only one really stands out: Yosemite ranger Shelton Johnson, a poetic parks enthusiast who made me proud my taxes help pay his salary.

Dexter's a daddy

Television's favorite serial killer, "Dexter," returns for a fourth season Sunday (9 p.m., Showtime) with a whole new life - wife, baby, stepkids - and the kind of sleep deficit that even those of us who don't moonlight by cutting apart bad people can probably identify with.

Poor guy needs his sleep, but if he sleeps, who's going to mete out the justice that the justice system can't seem to? And how long can Dexter (Michael C. Hall) let his night activities lapse, especially now that there's a creepy new killer in town (John Lithgow) who doesn't seem to share Dexter's code of ethics?

And there's Special Agent Frank Lundy (Keith Carradine), who's back causing problems for both Dexter, his favorite lab guy, and for Dex's sister, Debra (Jennifer Carpenter), who'd just about gotten over him.

Based on what I've seen so far, we're looking at a killer season.

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