If I could have it “my way,” I would start on Low A and go all the way to High C. This would be 38 strings, of course. I do use that High C a lot, especially to end a glissando in the Key of C. I miss it on my Ravenna, which only goes to A at the top, 34 strings. I have even played the harmonic on the highest C Ravenna has to get the sound of that High C in a piece.
I guess it also depends a lot on what “tuning” you use. I am a C-tuning lever harpist, since the pedal harp is tuned that way, so I need the Low C and the Highest C in the Key of C. If you tune in E flat, that would be much less important. I know some E flat-tuning lever harpists who do not go below the Low E flat when they play, so if that were the lowest note, the harp could go up to E flat for the highest note and be very useful (still 36 strings). My pedal harp has that nice High E, and I use it a lot, too. Just call me “Harpo” with all my glissandos, Biagio, ha, ha!
I did a concert at a retirement home last summer, and the nice woman who arranged it said to “play whatever you want as long as it includes LOTS of glissandos!” so I did not disappoint them, ha, ha!
Have a great day, all of you,
Balfour