In terms of strictly "getting rid" of your excess furniture, I would suggest contacting an auction company and having an auction sale. Just last month, I attended one of those types of sales where bidders bid on chairs, executive tables, etc. The company can earn more money that way, although a longer process depends on the auction company, its hours, and whatever percentage they pay. Usually between 10 and 15%. BUT … they will do everything in their power to get the maximum price for that furniture.
You can contact furniture stores and see if they would buy it, but your strategy is, and always will be, to negotiate the lowest possible price. You may have to haggle a bit if that's what you choose.
The parking sale, as you suggested, might also be a good idea. But that would involve moving furniture in and out of the building for items that are sold or not sold.
Either way, I only offered my 2 cents … good luck.