I can listen to Opeth at anytime but when I like it most and it's power is most effective is when it's dark, and/or rainy, cold, damp, cloudy, dreary. At these times is when their music really comes alive for me, especially the first 5 albums.
Pretty much everywhere. Mostly when I go to bed though. I always go to sleep listening to music. Some nights I hardly get half way through the Moor and other nights I go through Still life, orchid, Mourning rise and usually pass out during BRI. I sometimes randomly blast Opeth throughout the house when I have parties or people over. Theres really always music going. Alot of the time when im driving too.