I don't see much value in the membership unless you are going to TTR as your almost exclusive vacation resort. It appears overpriced compared to just booking through Orbitz. The perks aren't that significant to justify the cost.
I agree with a lot of what was said here, however it was worth it for us because we negotiated what we wanted, including - -a couple free weeks AI as part of the contract -"trade in value" on our other resort contract -airfare discounts the first two years, and ongoing if we choose -poolside and other services so, really you will know if its for you. As a matter of "doing the math" if you are going to go to TTR once a year for at least 5 years, it will cost about the same with some extras. twice a year or more you will save some money. more than that... hard to say...
