Right now, a lot of people are trying to rent their timeshares, so you want to price your week competitively, market it well, and make sure you have a lot of traffic - because you have a lot of competition. I personally use these cheap or free websites to post my Ads:
TUG Timeshare Marketplace - http://tug2.com/timesharemarketplace/
1 year Membership - $15
Ads - free up to 25
Membership - $14.99 for 12 months
Timeshare Rental Ads - $24.99/ea for 6 Months
Timeshare Resale Ads - $59.99/ea for 12 Months
Membership - free
Timeshare Rental Ads - $19.95 ($24.95 - floating weeks)
Timeshare Resale Ads - $34.95
There is also a list of resale websites at the top of the Buying, Selling, Renting, board that you may want to take a look at.
Some people don't like Craigslist, because you get a lot of scammers who respond, but they are painfully obvious, and I just ignore them. Another tool I use to eliminate the scammers is that I only accept payment by Paypal which requires a verified bank account or credit card to be registered.
On Craigslist, you need to create a Craigslist Acct., create 3 different Ads with different titles and wording, and rotate them every 3 days. You don't have to rewrite the Ads - if you create an Acct. they will be saved in your Acct. and you can just use the "renew" function, to renew the oldest Ad every 3 days which will bring it to the top of the listings.