There is a single question that you can. and should answer here and now. This one question concludes everything else: Do you want to do timesharing?
If the answer is "no" (which is likely the case, given your question), then everything else is inconsequential. You have no obligation to do something you don't want, and you should never do something you don't want, no matter what someone says, or what good reasons they might bring up.
This sounds quite obvious and superfluous to say, but that's really all to it.
To take advantage of the "special offer", you (your fiancé) have agreed to attend a 2-hour promo. Since you said "called", do you actually have this in writing? If not, absolutely make sure you do, and before the trip. You do not want to discuss the terms, surprise fees, and what was said and wasn't, and what you apparently didn't understand properly in retrospective. That's a very bad situation to avoid.
You want exact conditions, written on paper, before going. Every not totally fraudulent company will give you these (even though, unluckily, they are not strictly required to do it in your case, phone deals are exepted from the rule that says they must).
Then, if you want to do the trip and avoid extra cost, you will have to comply with the agreed terms as written, to the letter. That is, you need to attend this presentation for the full 2 hours. But you do not need to do anything more, and in particular you do not need to agree to, buy, or sign anything. You don't need to become the sales person's friend either (secret tip: you're not anyway).
Since you want the "special offer", you must look at / listen to what they show / tell you, that's the agreement. But you need not disclose anything about yourself, or discuss with them, or even buy something.
Any kind of discussion is, from your point of view, detrimental. There is nothing you can win. You do not want to buy something, you've already decided that. You do not need to "prove" that to yourself or anyone else. On the other hand, you are certain to lose a discussion against an experienced salesman specifically trained for the task. Thus, the best thing you can do is avoid discussions.
But even if you get into a discussion (you probably will, very few people manage to be impolite enough to avoid them), and you lose the discussion insofar as you would be a complete idiot if you didn't take that great offer... you can, and should, still say "no".
You have the right to be an idiot and lose out on the greatest ever offer. There needs not be any reason for that other than "Because. I don't want.". You can say that more politely or less politely, as long as it remains "no", it's all the same. Again, you're not intending to become the sales person's friend.
Also, never, never ever, follow them into their office. Stay in the hotel's meeting room or whereever the crowd is. Not only will a one to one session be a lot more stressing, also see last paragraph below for a good reason.
I personally deem the advice to leave your credit card and wallet in the safe a bad approach. It's like going to a bar when you are an alcoholic. Leaving the gin bottle at home won't prevent you from drinking, if you go to a bar. You must either have an ironclad will, or you must not go to the bar in the first place.
On the one hand side, you can sign a binding contract just fine without your wallet, so it doesn't truly protect you. In the strictest sense, even saying "yes" without signing a contract is a contract (though it is unlikely a company like Hilton will attempt to enforce that). To be on the safe side, just don't say "yes", ever.
On the other hand, if you know that you are so suggestible (read as: weak) that you believe you might otherwise (if you had your wallet) sign something although you decidedly don't want it, then by all means do not go there. Don't. That's a lost cause.
If you are unsure, scratch the offer, consider the $99 that you already paid forfeited, all in all this will come a lot cheaper.
If, despite all, you later find out that you were silly enough to sign up anyway, hand in a cancellation note within at most 3 business days. Actually, if the contract is signed in Florida (but be careful about place of jurisdiction!) you should have 10 days, but do not needlessly tempt your luck. Better be safe than sorry, do it within 3 days.
Do not do this on the phone, do not talk, do not discuss. You will lose the discussion. Written on paper, handed over with a witness (registered mail will work, too). You need undeniable, hard evidence of having handed in cancellation.
Also relevant: 16 CFR 429.0, 16 CFR 429.1. Note the wording "place other than the place of business of the seller (e.g., [...] hotel or motel rooms, convention centers, ...".