I’m possibly running into a very similar situation with the same island. Granted, we haven’t officially committed to anything yet, but it’s one of the ideas on the table for us.
If we go this route, we’ll be paying for our stay as well as that of our parents. If the house we opt for holds more than that, then I did debate whether it was appropriate to offer up the additional rooms for a “fee” that would be a bargain to guests, but in line with the expense. Ultimately, I had a gut check that is very much in line with what Miss Orchard and j_jaye have pointed out.
To be honest, it kind of puts that plan off to me. I don’t want to be seen as asking guests to help pay for the wedding that I have invited them to, and that’s kind of what I’d be asking if the house is also going to be the venue. On the other hand, I would jump at the opportunity as a guest, so I don’t think it’s completely unreasonable.
My suggestion, and something I have talked about as a possibility with my mom, is that if we go this route with far more space than what we will actually need, I may have her end up being the “contact” and the person with whom to make plans to stay in that house. That way it would be presented as she’s renting a house with more space than we would take up and if others wanted a relatively low cost place to stay with other members of the party, they are welcome to work with her. We, of course, would reimburse her for the house expenses for us, her with her plus one, and the future in-laws. However, in all likelihood, we’ll opt for a house that holds the number we need it to hold and it won’t actually be an issue.
As for issues setting up, that’s just going to depend on you and your vision for how the wedding will look and what you need. If we end up choosing this option and end up with a house that’s got more rooms than what we need, I know my vision is so simple that it really won’t matter that other guests are there. But, if you’ve got something even slightly elaborate in mind, it could be very busy around the house on the day you should otherwise be relaxed.
Also, fair word of warning that I think you need to communicate with guests if you offer them this deal: A house may “sleep” 22, but may not have very many bedrooms. If you’re basically charging people about $100/night (which is only slightly cheaper than B&Bs on the island and more expensive than some hotel options), then they will not be pleased if they are on a sleeper sofa in the middle of a living room with two other couples on sofas around them. Even if someone is “fine” with sleeping on a sofa in a public space, someone who has paid for a room probably isn’t going to be thrilled and there’s another guest in his or her pjs when they go downstairs in the morning. This also doesn’t address the bathroom issue that could arise.
Ultimately, I’m not saying you shouldn’t do it. So much of it depends on your guests and your plans for the event. However, if you do it, I would advise treading VERY carefully down this road. There’s the etiquette issue of possibly being seen as helping foot the bill for the venue you picked while also concerns about expectations for the price.