Can we do a "Pointless Poll" on this please?
Let me know where you are and what you say, vall-ett or vall-ay.

As long as a century ago, vall-ay was the pronunciation in the USA (or at least in the eastern USA). It appears in a poem of that time, and the pronunciation is necessary to the rhyme scheme.

Aside: the poem is humorous, punny TEd, you'll love it, and well worth the reading -- but unfortunately too long to post here and unavailable by link. I'll transcibe it elsewhere, and then provide a link.