What should I wear to my husband's 40th?

It seemed like such a good idea at the time:

Please wear your favourite thing (and your swimming costume).

It's B's 40th on Monday (let's skip over the oh my goodness where on earth did the last ten years go bit) and we are having a party.  It's a These are a few of my favourite things party, because that way he gets to have all the stuff he likes: champagne (on offer), hot tub (hired - hence the swimming costume), karaoke, disco, roast pork, poppadoms (the curry house is bringing 100 round at 6.30 on the evening), ice cream... All in the garden (if the rain ever stops).

So obviously, the dress code is your favourite thing.  Which seems so easy, until you think about it.  Because actually my favourite thing is the thing that makes me look most like Angelina Jolie and least like a slightly stressed, slightly flabby, slightly saggy mother of four. (Angelina has six, or seven, which must be easier, economies of scale, and all that). And I don't seem to have a magic wand handy.

I've narrowed it down to the fact that I can't buy anything new (because that feels like cheating) and I genuinely like dressing up (in the posh, not stupid, sense), so where plenty of people are planning on coming in their pjs, that's not for me. I want to look splendid, and pjs (or at least my pjs) aren't splendid.  And I'm definitely wearing these:

But what else?  Because while B might be quite happy to have me in just gold sparkly shoes, I'm not sure the Scottish Borders is ready for that.

Here's the shortlist.... leave a comment letting me know what you think. I don't promise to do what I'm told, but some independent thoughts (and not that I need my legs waxing, that's next Tuesday) would be very much appreciated.

We could go sort of smart casual-ish.  These are absurdly flattering jeans (although better with shoes), and it's a nice top, although looking at the pictures I'm not sure it doesn't make my body look long and my legs short, which they are, but still....

Or the other extreme.  Nothing casual about this. I bought it for a friend's wedding in 2003.  Still love it:

 
Downsides: it appears to make me fade into the background, but I'm hoping that's just the picture.  Oh, and no bra... possibly unwise in a woman who has breast-fed (and sort of appears still to be breast-feeding) four children.

Or this.  I made this dress out of fabric my brother bought back from his gap year in China. Quite proud of that, but not sure I still have the figure I made it for. 

Or what about this?  I bought this in a charity sale about two weeks ago for a fiver.  It makes me feel all flirty.

B's always been quite a fan of this dress, which I bought with a friend (the same one whose wedding it was, as it happens) in about 1999.  I'm not convinced it does that much for me, but he wants me to put it to the vote:

He's also quite keen on this one, my amazing coat, bought on a whim for my birthday about five years ago in a funny little shop by Baron's Court tube, but I haven't got anything that really works underneath it (this purple job's a bit of a poor compromise), and as I've mentioned I'm not sure the Borders is prepared for the alternative:

So what about this?  Bought for the day after our wedding, when all the people my parents like but we don't know were invited for lunch.  Got a bit of a red wine stain on the front of it from a wedding about a month ago, but you can't really see it...

Or this? It is one of my favourite things, after all....but is it really that sort of party? And am I prepared to risk it?

Answers on a postcard (or in the comments box, if that's easier...).