What others have said here about deducting the mortgage interest and property taxes is true! It starts on your federal tax return as a Schedule A deduction and, for most states, carries to your state tax return, too.
As for the concern about multiple contracts, it is not an issue because you can use your points from various contracts together for one stay (if you choose to) and therefore it is considered one "home." If you were unable to comingle your contract points to stay at various locations then it would matter, but the way
DVC runs the point system it is one "home" because you are one "member." Now if you have a similar timeshare through Marriott or another company, that would be a separate "home" and then you would need to see which 2 give you the most bang for your buck!
For those of you with motorhomes or houseboats, if they have sleeping, cooking, and bathroom facilities they are considered a "home" so you need to pick your best two "homes" and use the mortgage and property tax for those two.
As for the other part of your dues, unless you rent your points these are in no way tax deductable! But if you do rent points, you generally have to declare the income and can therefore take the expenses, i.e. dues, to offset your income. This concept is not for the faint at heart, however! Make sure if you are renting points that you keep good records for your tax professional so they can keep you out of trouble!
And if you are in Northern California and need a tax professional, I would be happy to help!
Blahnde