I've never come across anyone who's heard of that film (it's a mysteriously perennial family favourite). Wow.
Glynis is a nice name; I like it. As you say, it's definitely 'sweet'. To me it's firmly an older name, though - I can't really imagine a
Glynis younger than middle age.
Glenys and
Glenna I'm not a fan of.
Glenda's okay.