In first place, a piece of music I have raved about in the past [clicky] "Recuerdos de la Alhambra (Memories of the Alhambra)" by Francisco Tárrega. Last time I gave a version by John Williams (exquisite) this time by way of a change this is Ana Vidovic ... many players have a tendency to race the piece, and she doesn't... she's also (as the Legatus would say) "splendid" in the looks department..
Second, Mozart's "Laudate Dominum" from the 'Vesperae solemnes de confessore, KV 339' ... just to show that there is no right way to arrive at classical music*, I first heard this in an episode of Inspector Morse.. I love it... at our wedding, the current Mrs Steve the Wargamer walked down the aisle to a version of this played on the organ - I think this version is monumental, but by way of contrast I would also recommend those by Emma Kirkby and also by Katherine Jenkins...
* ...to prove it I can only offer in evidence that my enjoyment of opera, yes, opera , came from Malcolm McLaren, and yes again, he of the Sex Pistols..
Third - this is the most peaceful and mentally easing piece of music I think I have ever heard (though Thomas Tallis is also to be recommended)... and this is just the most beautiful rendition of it (by the choir of New College, Oxford)... darken the room, find a comfortable chair, get a glass/mug/cup of your favourite concoction and lose yourself...