I'd say the song that leaves me most with my jaw on the floor is the Kinks' "Lola". It's not my favourite song, by any means, but so many little embellishments add up to make such a lovingly crafted piece:

• the unconventional-yet-perfect opening I-ii-iii chords
• "down in North Soho", indicating down in spirit, not place
• the seedy scene-setting: cheap champagne
• the foreshadowing of a titular rhyme: "Cola, C-O-L-A Cola"
• "dark brown voice", recalling the husky Cola
• "lo lo lo Lola", adding another hook to the end of each stanza
• repetition of stanza structure twice more following scene-setting, documenting development of confusion through two examples
• especially the catchphrase-ish "why she walked like a woman and talked like a man"
• repetition of the champagne motif for the first chorus
• "electric candlelight", again illustrating cheapness, but this time with the motif that not all is as it appears
• "I almost fell for my Lola", recalled with "I fell to the floor" in the next stanza
• "I fell to the floor" followed by "I got down on my knee", highlighting the oddness and multilayered symbolism of the latter action in context, especially with the chord progression change
• "girls will be boys and boys will be girls / it's a mixed-up, muddled-up, shook-up world / except for Lola"
• "I'd never ever kissed a woman before": he still might not have
• "I know what I am and I'm glad I'm a man, and so is Lola": the most perfectly executed ambiguity ever
• repetition of hooks ad nauseam to close, along with that triumphant I-ii-iii, keeping the earworm wormy for hours

So, WAtMM, what songs blow you away with songwriting - either through little touches, or through pure innovative brilliance?