Some great observations here, but I do think we need to mention that How I Met Your Mother represents the perfect storm: it has a high concept premise while maintaining the "people hanging out" vibe, allowing executives to have their cake and eat it too. What's interesting about HIMYM is that its high concept took a lot longer to burn out than with other series: it's only now, five seasons into its run, when it's becoming clear that the concept was more burden than benefit in the long term, and it will be interesting to see how the series negotiates that as it continues.

THAT WAS THE BEST SEASON!

[In all seriousness, I'd give Season Four another shot - it's a bit jarring after continuity-centric Season Three, but it comes together so gosh darn well.]