I resist putting Picard's faible for Earl Grey on a level with Janeway's obvious coffee addiction! And it's not his weakness anyhow.
And just to be perfectly clear, that's something I enjoy a lot in Voyager: taking this particular bit of weak lore and making it more real.

I think Picard's weakness is Q.

Or Lwaxana Troi, as somebody else already stated.

Can someone remind me what Whorf's plastic barrels are about? I have a faint inkling but cannot fully recall.