Regular champagne is a pale gold color, so a touch of Wilton Golden Yellow, perhaps with a smaller bit of orange, should work well.
If using Americolor, I would go with just a touch of egg yellow, which has an orange tinge to it.
Theresa 
I was going to suggest trying the copper color with some pink. I used to own a bridal accessory business and rum pink is a color option for some wedding accessories, for example, pearls used on custom made tiaras can come in white, ivory, light ivory, rum pink or champagne. Rum pink is a dusty light mauve/pink color. It sounds exactly like the color you wanting to achieve.
Here's a link to a friend of mine's website where she gives color options for pearls on the pieces she makes.
http://amysbridalaccessories.com/samples.shtml
Scroll down to the bottom where you see the pearls, You'll see rum pink freshwater pearls. Is that close to the color you want?
If it is, maybe someone else can give color combos to try.
I have champagne colored luster dust. It's a golden pinkish color... I think that your original idea might work!
Rachel
Cakerator:
Is this the "champagne" color you're looking for? If so, I did a wedding two weeks ago to match this color.
http://davidsbridal.com/bridal_gowns_detail.jsp?stid=2660&prodgroup=92
For WEEKS, I stressed out about matching the icing to this color. I asked questions here, with the local cake shop, and then I started tinting icing!
I finally achieved EXACTLY this color of "champagne," by mixing "copper/flesh" tone with a little black. Just a touch of black.
When I picked up the bride's swatch, however--it was nothing like the computer's version--it was a simple off-white/ivory! WHEW!
So, I guess you'll just have to see...
HTH,
--Knox--
that dress is beautiful. thanks for sending the pic for reference.
i think what i want is more like a pink - champagne color. i was going to pair it with gold for a 50th anniversary cake. at this point, i have rethought the whole thing and i think i'm going with a dusty rose with gold accents.
but, i may change my mind again. LOL
thanks again for your help.
Quote by @%username% on %date%
%body%