Don't offer any personal info. We did this in January for a weekend in Tahoe. We sat through the 90 minute presentation, had plenty of coffee, and while my wife engaged in very curious and valid questions I did math on their little piece of paper. They love to show you your lump sum investment, what the yearly maintenance fees are and what inflation will do to vacationing in the future, they like 3.5% for inflation?
Anyway, I sat there and did the math on the sum, maintenance, and inflation costs and easily saw that if you invest that money or spend it every year you can get a better return, with no locked in money. If you invest that money for 10 years (our accumulation phase) it basically adds to our vacation funds we've already planned. The cost vs hassle is totally not worth it. Listen to the presentation and use logic to prove to yourself it's not worth it, cause the deal sounds great. At the end of it, it you find yourself considering it, walk away, they're are websites dedicated to people who will sell you their time shares for 10% of what they want you to buy it for and others who will PAY you to buy it from them.
Go in looking like you have little income, jeans and a t-shirt. Downplay your income, they will offer you a smaller "down payment" amount and I think it makes the presentation more fun.
Oh and this deal is only being offered today; did I tell you about the bonus rates we'll add for free and how we'll cover the maintenance fees?