My fiance and I want to go to Vegas and get married on a special date. Would it be very appropriate to invite a group of our friends where they are thinking this is a group bachelor/bachelorette party until we get there and then inform them that this is a surprise wedding instead? I feel it may be a little distasteful since it would really be our wedding and they have paid their own hotel/airfare.
The real problem here is that the bachelor/bachelorette parties are paid for by the guests. The couple is treated. This is the only party of its kind. Usually, the rule is you invite, you pay. So, you couldn't invite them to a party like this--the couple doesn't plan or invite because they are the honored guests. If an attendant did, you would be paying for their lodging. And, you couldn't ask your guests to pay for your wedding, which this would actually be.
So, it would be best, if this is to be a surprise, to be some sort of gathering. But, if you invite, you would pay for the gathering--some sort of reception. You are not obligated to pay for anyone's travel or lodging costs if they are not in the wedding.