Since nearly everything suggested I'd agree with - felt I'd pitch in with some more ideas, and some of an older vintage.
SHE LOVE'S ME - original cast 1963 - the kind of musical they almost never make anymore with a strong book, real romanctic comedy. Barbara Cook in her prime, singing more devinely than she even does today. The songs by Jerry Bock and Sheldon Harnick, show character, set scene, even manage jokes and also manage to express the curious joys of being in love.
PAL JOEY - probably look for the 1995 Encores performance - Rodgers with Lorenz Hart, in the first anti-heroic musical, Joey's a nasty piece of work and admits it in song, his older woman Vera knows exactly what she's paying him for. While the arguments may rage as to whether the book will ever be fixed, the songs are like a perfect Martini.
FINIAN'S RAINBOW - the recent Irish Rep version is very good, but the original has Ella Logan & David Wayne - Harburg's lyrics just fix themselves into your brain, even with made-up words and outrageous rhymes. The whole score is fun, and silly, and you may never look at the moonlight the same way again.
SECRET GARDEN - Broadway cast - Lyrical, melodic, beautiful songs of love in 'Lily's Eyes'; I'll even forgive some of the most peculiar English accents I've ever heard for this score.
Happy shopping!
John Gielgud remarked to Coral Browne, "you know, Coral, Judi Dench is going to play Lady Macbeth."
"Oh, then I suppose we shall have the postcard scene!"