"...and there's nothing worse than that pause during a great dinner party where you try to decide if your guests are worthy of your last bottle of your favourite wine..."

LOL. I know that feeling. Truthfully, I'm starting to bogart all the good ones.

I haven't been shopping for those big chards lately, but I used to love them. Toasted Head, the Kendall Jackson Reserve my father-in-law brought over recently (REALLY oaky/buttery, but I forget the vintage).

My local wineries say the local fruit isn't suitable for that style, so they generally make the fermented in stainless version. Two of the best in my area, IMO, are the Mount Palomar chard - balanced with some oak and butter overtones, very reasonably priced, but not a BFC - and the Leonesse chard in my cabinet (I'll check the vintage if you want to roll the dice) - brilliant, beautiful fruit, but expensive.