Ok, here's a rundown on some great albums to have on hand for laying down a mellow, soulful and sexytime vibe for you and your mate. These are old-school.
Really Old School-
The Platters - All-Time Greatest Hits
The Platters were an important mix between the old-time pop music and rock and roll music, and sometimes they got it perfectly down to be timeless. The Great Pretender and Smoke Gets in Your Eyes and Only You you've all heard and hummed, but you might not have thought to check out the Platters.
Al Green IS sexytime music. That's all we need to say.
Let's Get It On [Deluxe Edition]
Marvin Gaye was the man. Give this album a listen if you've not heard it through.
Mellow Gold (Yes, I know that's a Beck album, I wouldn't play it for this, but I would try...)
Van has a bunch of great albums, this one is mellow and folky but still smooth.