Re: How many frets do you prefer?
21 or 22 is fine for me. I think any higher doesn't really play to the guitars strengths.
Think of it like a human voice, you have a range you speak in, it goes lower when you are speaking quietly, tiredly or when you are speaking aggressively, it goes higher when you are whimsical, or when you sing with power. At the top of your voice range you have the falsetto, a range that your voice isn't naturally adapted to use, a range that sounds a little unnatural and imperfect, but is suitable for time to time for musical effect.
I think the same way about the fretboard, I think the most beautiful and powerful range of the guitar is in the midrange, though as a stringed instrument we have an advantage of strong clear low notes due to the nature of open strings and frets (whereas a wind instrument or voice begins to get windy or run out of steam at the lowest part of their range). The best part of the guitar fretboard, to my ears, is between maybe the third fret and the 10th fret. It's a place that we can get warmth and power that few other instruments can. If you look at sheet music written for the guitar, there is always a little note saying '8vb', indicating that the piece is meant to be played an octave below what is displayed. The guitar IS a low instrument, and I feel like the lower-middle frets are the ones that take advantage of a fairly unique tonal range that we can access. Try playing with an alto sax player, a female singer, a bass player. You'll quickly realise that you have that range all to yourself, there will be zero clashing with any other instrument in the band.
The upper-midrange of the guitar still sounds beautiful, though the notes start to lose their sustain, and they lack the power of the lower notes. This is like the beautiful, slightly breathier part at the top of your range. It can be used to add accent to something, it can be used to add beauty and lightness to a solo or melody. It's a pretty range, not a warm range.
Then you hit the top of the guitar, those last few frets, maybe from the high A and up. This is the guitars falsetto range. The nature of the physics behind a fretted string instrument start to show their weaknesses up here. You lose the sustain, your notes begin to sound plinky. Even the lower notes down on the other 5 strings have lost most of their warmth and body as the distance between frets has gotten smaller. This is the range for character, a brief display of your virtuosity and range, a few small dips into the range to pull out that plinky/sharp texture and you move away. Use it for the colour, not the 'tone' it brings. Use it because you have to hit the notes for the sake of the melody, not for the sake of playing up high.
That's why I don't feel the need for more than 22 frets ever, I feel like anything higher and you are starting to play out of the natural range of the instrument. These are just my thoughts, keep in mind that I've taken courses in university on what amounts to the philosophy of music/art, so I've spent more time thinking about this kind of stuff than is probably normal, so take it all with a grain of salt.
