whts the best slow acoustic song in classic rock? i mean songs like beth, hard luck women, goodbye to romance, tangerine, etc?
If by Beth you mean the Kiss song, then honestly you need to listen to more music...

I like 'Thank You' and 'That's the Way' by LZ, 'Wish You Were Here' by Pink Floyd, 'Angie' By the Stones, 'Behind Blue Eyes' by The Who, 'Norwegian Wood', 'Yesterday', 'Blackbird' by The Beatles, 'Teach Your Children' and 'Suite: Judy Blue Eyes' by CSN, 'Empty Chairs' and 'American Pie' by Don McLean, 'Tears in Heaven' by EC.... there are so many.

Simon & Garfunkel? Lots of options there. Pretty many ANY early Bob Dylan.

Led Zep have another slow acoustic song, goes for about 8 mins and has some electric guitar bits at the end. The name escapes me though. But a lot of people seem to know it. You might also like to try and figure out what that one is.