What are sensible/rational character limits in a database e.g. for a persons name
I think some of it goes back to requirements. How much of a name are you storing? Do you ever want to keep the "names" separate (like first, middle, last)? Do you want to handle multiple middle names?

I'd say 50 characters should be fairly sufficient for each name if you wished to separate them out. (That will be way more than enough for most names, but will also cover names that are larger.) I'd also probably go with VARCHAR than CHAR for names since they vary so much.

If you were going to put the full name in one field, I'd go with 150 - 200 characters then.

Again....it all goes back to requirements...what do you need?