I am planning a fundraiser for a non profit organization. Any ideas on how to get good silent auction items donated?

And then go door to door in upper class neighborhoods

I'd assign your best "salesperson", the one who can sell ice cubes to an Eskimo, as they say, to sit at the phone and call all the businesses in town. Even better--to visit them personally. A charmer can talk to someone and get them to donate MUCH more than sending letters out--it's harder to turn someone down in person but it's VERY easy to toss a letter requesting something into the garbage can. But make sure that you will reciprocate for your donors--tell them that their name will be prominently displayed on the item and listed in your program or whatever. Also remind them their donation is tax deductible. Don't forget the non-obvious donors. Approach museums and zoos for season passes, for instance, or a photographer for a portrait session. Gift cards are GREAT! Also try local "celebs". Get the mayor to offer his services to wash someone's car, or mow their lawn, or cook a dinner for the winner. Get the local pool to donate a pool party for a set number of kids. It depends on your organization and how much you are supported in your community as to how well you will do. If you are new and unproven, it will be harder. Good luck.