Where to sell a second-hand suit in excellent condition ?

I have two or three second-hand suits which have hardly been worn and look virtually new. Also a lovely double-breasted blazer in dark navy / black with brass buttons chest size 42 inches. These clothes are in excellent condition and far too good to throw away. But I never wear them. So they need to go. Can someone tell me what they do with their own old clothes, especially where they cost a lot of money when new but have hardly ever been worn for several years ? I hate to simply throw them away when they look almost new. Does anyone here on the Forum have some ideas ? Thank you.