We have been guests on numerous occasions in various areas, and have had guests aboard on numerous occasions similarly, for as long as a couple of weeks at a time.
Obviously compatibility is numero uno.. and that's something very difficult to quantify ahead of time unless you already know the guests well. Even being family doesn't guarantee a harmonious cruise, does it??
But we find ourselves facing a bit of a double standard.. when we are guests we are happy/anxious to pay our share.. esp if we are being treated to an area we'd never otherwise enjoy. We're happy to pay moorage, food, customs fees, essentially the real costs of their having us aboard over that time. Sometimes we feel we have to 'push' that support but in the end it only seems fair.. especially if they've taken us to areas where they may have not gone had we not joined them..
But on the flip side I'm a bit embarrassed when they return the favour as our guests.. we never ask for anything, but they of course reciprocate, and I believe they're fine with that but I find it a bit uncomfortable. Largely, because rarely does the presence of guests change our plans, or add to expenses beyond food and drink..
In the end we accept it, of course.. and ultimately it works for everyone. But this is all a bit different from saying.. wanna come sailing? only $20/day!
Our arrangements have been between sailors, we've (each party) had our own boats and fully understand the logistics of cruising and upkeep... When dealing with nonsailing guest who would have no idea perhaps it is best to set some kind of support cost(but, I'd say, only if it's beyond a daysail) If we invited a workmate for an afternoon sail I'd certainly not expect them to bring cash.... beer maybe.... but not cash