If you use the Search function for Donate For a Cause (DFC), you would see that there are many threads discussing in detail what it does for TS owners.
I'll try to put it in a nutshell. As you found out a couple years ago, DFC (or any other charity that deals with TSs) will not let you just simply "donate" a TS. They will charge you thousands of dollars (sometimes referred to as a service charge). They will actually sign the deed over to their name thus removing you as legal owner. It should be a quick, painless process. But, as said before, it's a very costly process.
If you're willing to be patient and use a little "elbow grease", there are cheaper ways of getting rid of your TS.
1) Try selling it:
http://tugbbs.com/forums/showthread.php?t=44
If you find that there is no resale value in your TS, then try suggestion #2
2) Try asking the resort if it will take your TS back:
http://tug2.net/timeshare_advice/give_back_timeshare.html
While you're trying that, concurrently try step #3:
3) The free give away section here on TUG:
http://tugbbs.com/forums/showthread.php?t=132509
You should be able to get rid of your ownership following these steps.
As for being able to "write off the property", the answer is Yes. But you can only write of the Fair Market Value (FMV). If you can't sell or give your TS away, then the FMV is about zero and hence, that would be about how much you could write off.