Two that won't appeal to everyone, but would probably be enjoyed a great deal by those with an interest in the subject matter.
The premise of "Captains" is very simple - William Shatner interviewing the actors who have played Captains on "Star Trek" - Patrick Stewart, Avery Brooks, Kate Mulgrew, Scott Bakula, and Chris Pine. If you don't give a whit about "Star Trek," there's no reason for you to see this movie, unless you have an intense (and probably unhealthy) fascination with the ego and personality of William Shatner. But if you are a Trekkie, or Trekker, or just casual fan of the show, it's worth spending a couple of hours with. Shatner is a surprisingly good interviewer, with an interesting technique - he talks about himself a lot, but in doing so creates a conversational atmosphere that makes it easy for the subjects to open up. It's an interesting mix of people (Christopher Plummer, a memorable villain as a Klingon in "The Undiscovered Country" is also thrown in for good measure), and throughout we learn that Stewart really is as classy as he's always seemed, that Brooks is a bit of strange duck, that Mulgrew is refreshingly open about the costs of success, that Bakula is just as down-to-earth as one might imagine, and that Pine seems to be having fun enjoying the ride. As is Shatner - after all, he's got to be one of the quintessential "laughing all the way to the bank" stories of our time.
The premise of "elBulli" is equally simple. For those not into food, cooking, or fine dining, elBulli was a world-famous restaurant in Spain, a Michelin 3-star restaurant renowned for being one of the birthplaces of molecular gastronomy. It was a very tough ticket - according to the page linked above, the restaurant would receive 2 million requests for the roughly 8,000 dining opportunities available during its six-month season. If you were lucky enough to be rewarded with a table, you would pay roughly $325 per person for a 35-course meal, and (I imagine) leave quite satisfied.
The movie takes simplicity to a new level - basically, the director and crew just turned the cameras on, and filmed some of the 42 chefs experimenting with new dishes and developing them to a point where they felt comfortable taking them to Ferran Adria, the man in charge. There's no narration, and no "question and answer" type of scenes - just experimenting, cooking, and preparing the restaurant. When it comes to running his crew, Ferran is the polar opposite of Gordon Ramsay. He's soft-spoken, never seems to raise his voice, and simply has to raise his hand and call for quiet to get everyone's attention. But it's clear that he's a hard man to please - in one example, he simply tells his chefs, "this is not good - please bring me only good things." Inherent in that simple statement is the notion that Ferran knows they know the difference; he sees no need to explain to them why the dish is not good.
Perhaps not for everyone, but both worth seeking out.