the melancholy of haruhi suzumiya episode order?

I'd suggest watching all of S1, then all of S2 (yes, all of Endless Eight), and then Disappearance. And then, if you REALLY love Haruhi, the so-bad-it's-hilarious Haruhi-chan/Churuya dvds. If you DON'T watch all of Endless Eight, I doubt you will understand Yuki's frustration and the reasoning behind Disappearance. You can see Yuki's expressions in each episode, especially in her eyes and the way she says stuff. In the first episode, she's more talkative and actually participates in the "fun". By Endless Eight's finale, she's almost in tears, at least by Nagato standards. You can almost see her WANTING to scream for joy when Kyon puts a stop to it, but obviously she doesn't. Her eyes do glow and she almost smiles. That's LIKE screaming for joy for Nagato.

The best way to watch them is by chronological order. The 2009 broadcasting offers season 1 episodes mixed with season 2's, though I suggest watching only the first and last episodes of the Endless Eight arc.... The movie, from what I know, is directly after the events of the series (after Someday in the rain, you know that episode about Nagato reading a book). お役に立てれば幸いです!!

it's a bit confusing to order the ovas and anime along with movies, i suggest trying wiki