+1 for Fargo and Glengary Glen Ross
I'd probably add
- Shakespeare in Love - it's the Bard after all!
- The Number 23 - some of the best narrative voice-overs
- The Usual Suspects- something about that back and forth between Kevin Spacey and Chazz Palminteri
- Serenity - gotta love that neo-antebellum dialect spoken in Josh Whedon's 'Verse
- Chocolat - as pleasant to listen to as it is to watch. Binoche, Olin, Moss and Dench all in the same film? Plus Sally Taylor-Isherwood doing the voiceovers? What's not to like? (Great soundtrack which includes some fine Gypsy jazz guitar if you're a Django Reinhardt fan too!)
I haven't seen The Number 23, but I agree with all the rest. Chocolat is one of my all-time favourites. Strange how with just a little change in the direction it could have been a real chiller.
I haven't seen the recent True Grit either, but I can quote ad nauseam from the John Wayne version! Likewise The Shootist and The Quiet Man (though any resemblance to an authentic Irish accent there is purely coincidental.
It's not so much the dialect, more the delight in the formality and rhythm of language. The Magnificent Seven (the original, not the cheesy sequels) is another I could listen to over and over.
What else? Casablanca, The Maltese Falcon, The African Queen. Any number of Thirties "screwball" comedies, but especially Bringing up Baby, His Girl Friday, and The Philadelphia Story. Scaramouche. Kiss Me Kate. West Side Story.
I suppose I'm just hooked on the oldies, but I must mention a couple more recent but in the same mould: The Princess Bride (of course!) and the magnificent Cyrano de Bergerac with Gerard Depardieu (in French, but the best /ever/ subtitles - by Anthony Burgess, no less!).