I'm not sure that length should preclude comedy. You may not think of it as such, but Wagner seemed pretty sure he was writing a comic opera when he wrote Die Meistersinger. Strauss too, when he wrote Der Rosenkavalier, which is actually my favourite Strauss opera, though it's not the comic bits I like best. I love most of the first act. Some of the shenanigans in the second act can drive me a bit potty, but the Presentation of the Silver Rose is sublime. Again the beginning of the third act can be a little tedious, but from the entrance of the Marschallin onwards its glorious. Maybe it helps that I first saw it in my early twenties in a wonderful production by Scottish Opera, with Helga Dernesch as the most beautiful Marschallin imaginable. I hadn't heard a note of the music before, but I was hooked and the trio in the last act had us all in tears. A most memorable night in the theatre.It's a little too long for a comedy. And with all my love to Strauss Der Rosenkavalier seems to me the least memorable. Maybe the case is that I've never seen it in the theater.