Personally, I've been playing RealMyst lately, and I'd forgotten how relaxing that game is for me. It reminds me of playing with my mom, and Myst Island, along with the Channelwood, Stoneship and Mechanical ages I find extremely peaceful. Also the music, love the music.
Another game is A Link to the Past. I know that game backwards and forwards, and it's always great for some mindless fun.