I've been really into watching old horror films on Netflix in my free time, the ones from the 20s-70s mainly. My favorites so far have been a couple by Roger Corman who did a few films based on Edgar Allan Poe's stories, with Vincent Price playing the villain (perfecto!).
The Masque of Red Death
This movie got me on so many levels: the humongous home it took place in, the costume design (especially during the masquerade), the hooded beings wandering through the forest, the occult aspect, the set design (there is a series of rooms they walk through, each one painted and decorated in one color--red, yellow, purple, white), the transitions, the experimental editing and coloring of scenes....I can go on, but it's definitely worth discovering on your own.
The Pit and the Pendulum
What brought me to this film was the mention of a Spanish castle, torture chambers and rocky beaches. This was truly a gem in the set design and costume sense as well as the color used for flashbacks. What I loved the most were the titles and credits--the image behind them was of water with paint being added to it. I loved the effect and the colors it produced.
Obviously, the things that I admired most were purely aesthetic, but that always seems to be the first thing I notice about any film. I loved Vincent Price though, and although some of the acting from some characters is a bit hokey, I still got lost in the world of Poe.