1) According to the research, many buyers start their search for property online... So your property will need to have a strong showing on the web AND reach the right audience.
2) List with a local REALTOR who is familiar with the area and where the buyers came from for comparable sales AND one that understands how to get additional exposure for your listing outside of their local multiple listing service (MLS) and the various sites that it sells the listing data to. See our listing plan at the link below for ideas on what might help your property's exosure.
3) Many sellers are tempted to ask for placement in print advertising where their audience might be... however, print advertising no longer shows itself to be as effective as it once was, consider electronic media... especially when considering the cost vs. return.
You want to target home buyers looking in that area. 80% of home buyers start their search online. By giving your home online exposure, the Chicago market will be able to reach it.
If you know of a specific demographic that buys vacation homes and you really want to go after them, then you could find out places where they congregate and start networking there.
Example: Let's say your buyers are likely to belong to a boating club in Chicago. If there is a forum, blog or message board where they visit, then you could go to those sites and network while casually letting people know that you have a waterfront property that you are selling. By having the listing online you can send the link to anyone who is interested and now you've reached your target audience.
I hope that helps.