It seems to me, you're being a bit harsh. It seems that you are at least a bit miffed, and taking it personally that she's choosing not to go, even though she declined politely and apppropriately. A wedding invitation, especially to a destination wedding, and especially to a guest who doesn't warrant an escort, isn't an obligation, and prospective guests don't owe you an explanation why they cannot or choose not to attend.
Also wedding ettiquette is not nearly as universal as the ettiquette books would have you believe. In central IL, "and guest" was pretty standard for all single guests, because everyone knows how much it sucks to be single at a wedding. Even bringing a platonic friend of either gender was preferred to coming alone. Inviting someone without "and guest" was tantamount to saying "we don't want you to come, but we do expect a gift". I'm not saying that's how your friend interpreted it, but expecting her to attend whether she wants to or not, just isn't reasonable.
I wouldn't have a lot of fun, even in Vegas, even for my best friend's wedding without a travel companion. Traveling alone, just doesn't appeal to me at all. It doesn't matter how great the destination, even if other aquaintences will be there (especially if they're all paired up, and I'm not), going alone is a bummer, especially since the bride is going to be far too busy to spend time worrying about whether I'm having a good time or not.
In choosing a destination wedding, you had to make some difficult choices, and you want your guests to respect that. You've got to be able to respect their decisions also, even if they're not what you would like. If you're taking it as personally as you seem to be, I'd ask why you don't expect your friend to take it personally that you didn't invite her bf, so that she would have a travel companion. It seems you're saying she shouldn't be offended (and it appears she isn't), but you have a right to be.



