As much as I love Sellers, for me the Pink Panther films haven't aged well. At the risk of heresy, I don't think time has been so kind to Strangelove either.
When I saw Putney Swope as a stoned teenager I thought it was the funniest thing. I saw it again and it was just an amusing period piece.
Another one I do love is A Fish Called Wanda, especially for Kevin Kline.