Depending on how long you are willing to hold them, you could list them on your local craigslist site in an attempt to save the online auction fees if you know what you want for them. If they don't sell after a couple weeks/month, then try something else such as eBay.
I recently sold/tried to sell most of the old currency that I had collected over the last 10-15 years or so, and basically determined there isn't much demand currency, especially most federal reserve notes. When I was asking at a local coin show, almost all the dealers just told me to bring the common ones to the bank or spend 'em, even the 1934 stuff as there was zero interest in those, even at face value. From the comments, it sounded like most dealers said they spent them as well.
The rarer star notes, silver certs, and red seals should have some value, but finding a buyer isn't as easy for currency in my experience. Hopefully, you'll have better luck.
