The only disco LP my mum owned was Nightflight To Venus - the first 11 minutes is one of the greatest openings to any album ever. I only had Kings Of The Wild Frontier to compare it to, but the electric drums on this are incredible - they hit you right in the gut, on vinyl, and I still love the whole 'ignition' bit and how it segues into Rasputin. No idea why this never made the CBS Top 100, Frank Farian was a genius (shame the rest of the album's a turkey).
An integral part of the experience was watching Boney M spin around in space at 33.3, illuminated by the red turntable light.
(After my dad died, my mum announced she was throwing all their vinyl out, so I went to Luton to bag all the Clancy Brothers/Wolfe Tones/Irish rebel records, but completely overlooked this one. Can probably find it in a charity shop for £50).