Here’s a beautiful dilemma for you, nature lovers: What’s better: getting out in the great outdoors, or sitting on your ass and watching all 12 hours and change of Ken Burns’ latest documentary, “The National Parks,” which takes you – you guessed it – deep inside the story of America’s National Parks system? It’s hard to decide, especially if you’re watching the Blu-ray version, which packs an absurd wealth of bonus material onto the already sprawling documentary and lays it all out in glorious 1080i. Spread out over six discs and housed in a handsome hardbound slipcase, “The National Parks” has the physical heft to back up its contents, which take the viewer on a stately, gorgeously filmed journey from 1851-1980, traveling from the Sierra Mountains to Yellowstone, the Everglades, Alaska, and pretty much everywhere in between. If you’ve ever had a question about an American national park, this documentary will answer it in rich, exhaustive (and, yes, occasionally exhausting) detail. Like Burns’ other major projects, this isn’t for dilettantes or the pathologically busy; you’ve got to be willing to put in the time to soak it all in. But for those with a real interest in the subject, “The National Parks” will prove a treasure almost as rewarding as those it spends so much time carefully examining. Pick it up now, while it’s deeply discounted at Amazon, and give yourself – or the nature lover in your life – a gift that’ll keep on giving for hours and hours.