For myself, I don't see him as particularly masculine, either physically or in personality. I have noticed that a lot of fics portray him as a big strapping manly man, which is not really my type anyway. I see him as tall but with a more average body type, not especially physically fit, a bit more effeminate, metrosexual basically. I agree about finding his domestic competence inherently sexy, but I've always been into men who are more androgynous/blurring traditional gender lines, so it doesn't need to contrast with him being extra masc to be attractive.

Also in fic Bertie is often described as extremely thin, but I see him as a little more solid than that. An otter, not a twink! More masculine than Jeeves in some ways and less in other ways.

I also usually read Jeeves as not being very sexual experienced. He just seems too reserved/prude/proper to have done a ton of philandering. Although with this topic and all others, I'm open to other interpretations and really enjoy hearing people's different perspectives!