Well, I'd prefer to be seen flaccid rather than semi hard since I am a "shower". I like to keep them guessing on how big I am semi or erect.
When erect I am pretty average size however, I have a Willy that shrinks and hides in nervous situations. I believe it stems from a humiliation episode when I was very very young that has plagued me for 50 years plus... So I would prefer a slight semi but chances are slim it will play along. Lol
I know of a guy who uses cialis, not because he has ED but because it makes his flaccid cock looker fuller. Like a semi but without the 'lift'. Apparently, after cumming, he is 'fuller' more plump than before which his GF enjoys more while she sucks him back to hardness again. He also free-balls all the time as his cock is more noticeable generally, which he likes because when out and about he thinks people notice it. And, of course, a brief squeeze or play brings it up, just to make sure people will notice it. I noticed it one time and it was a mutual friend who explained that to me.