American Bottle Auctions has long specialized in Western US bottles and could be a good venue for your soda bottle. It is worth checking with them at the very least.
Consider also one of the other specialty bottle auctioneers like Glassworks
Your bottle's value very much depends on the details of the condition ("great shape" to you may not be what another collector thinks) If rare and undamaged, the auction format is probably the best way to sell.