What to wear to Marianne's wedding?

I will attend a wedding on in mid-Sept. in Toronto. Marianne, my Parisienne friend Daniele's daughter, and her longtime love David, will marry.

The 6 pm. ceremony is followed by dinner and dancing; the setting is an old church in the centre of the city that has been de-churched, and is now a concert and events venue.

I'm leaning towards a pair of flowy palazzo-type pants, a shell and a gorgeous shawl- I want to look festive yet relaxed. The weather could be anything from summer-hot to early-fall cool.

The Toronto Film Festival is on then, and we can always spot the first-time visitors, like Joan Allen last year, in tweed and heavy turtlenecks despite 80-degree weather. The stylists evidently think fall in Southern Ontario is one step from a parka and dogsled.

TIFF makes for marvelous people-watching; I'd say the recognizable celebs are less well-dressed (except for parties) than the flocks of industry types, who appear in luxurious sportswear for breakfast and provide live sightings of jaw-dropping footwear as the tromp around the city arranging hair/makeup, press or simply being fab.

But back to the wedding...The convention is to avoid wearing black for the occasion, but I think my black pants would be OK: it's a second wedding, a hip crowd, and the pants are dance-worthy. I'd have to find a lighter shell, though, no black.

I have my eye on a silk shawl like this, a dark tangerine embroidered in lavender, black, cream, celadon and peach.

Or this one in a tribal design on cream silk:


They are both rectangular in shape. But I could change direction entirely, if only I had some more ideas!