Fortunately my local Odeon , although it got a couple of extra screens where the stalls were, never covered up the 1930s décor. http://www.cinemaprojectionists.co.uk/Odeon Richmond Web/odeon richmond.html
The local Gaumont closed, it's most distinctive feature was the sliding roof above the stalls, it could open to the stars (not in my time though).
Or they ended up as bingo halls , this one still in its original décor , Gala bingo Tooting
Or churches Rainbow Astoria , Finsbury Park. , now restored. The Who, The Beatles and more played there.