I've been obsessed with Saint-Saëns first Violin Sonata (D minor) recently. I'm a cellist, so I know my cello sonatas, but not so much violin. I love Saint-Saëns' concertos, cello stuff...but I'd never listened to his works for violin! Woah! It's incredible If you only have time for one movement check out the fourth.
Also Rachmaninov's first Piano Trio in G minor. My trio is rehearsing this for a performance in a few weeks, so I've been listening/practicing/reading it non-stop and I still love it. Delightful.
Also, non-classical guilty pleasure of the week: Lean by VHS Collection was the background music to a video someone sent me and it's oddly catchy. I've never heard of them but that's not saying much. :)