I don't believe any of your costs are adjustments to basis. You might have been able to deduct the costs in years you "rented" your points and reported taxable income.
Maintenance: Not allowable. The cost of maintaining personal property is never an allowable adjustment to basis. The cost of maintaining investment property is deductible in the year the maintenance was paid against the income produced by the property. If the property did not produce income, you can choose to capitalize your maintenance costs, but that requires attaching a written statement to each year's tax return documenting the capitalized cost. It's too late to go back and do that now.
Property taxes: Not allowable. Property taxes for personal property are only deductible if you are the legal owner of real property against who the tax is assessed. (You probably aren't the owner of real property. Is there a deed in Florida with your name on it? You are probably the owner of a right to use certain property subject to certain conditions.) Even if the taxes were deductible, they would have been deductible in the year paid, and they can't be added to your basis for failing to claim the deduction at the time. Again, if this was investment property, you could deduct the costs against investment income, or capitalize the costs on your tax return. It's too late to go back and do that now.
If in certain years, you "rented" your points, you might have been able to deduct your costs against your rental income. If you did that, then you have no costs that could possibly be allocated to the basis because that would be double-dipping, and if you failed to deduct the costs against your rental income, you can't go back and fix that now because the deadline to amend a tax return is 3 years.
As far as I can see, the only part of your annual fee that you could add to your cost basis is any fee that was required to maintain your ownership (was an investment in the property) and that was NOT maintenance or property taxes. Basically, Disney would have to come to you and say, "We know you paid $10,000 for your points, but they are worth $20,000 today. So either we buy you out at $10,000 and sell them to someone else, or you pay us another $10,000 to keep them.
