Vacationing with another couple...

We're not talking about the giant cruises or hotel takeovers here. We're talking about something much, much smaller and more intimate. We're branching out in our tastes, slowly. After having had one or two sleepovers with other couples, we're thinking that short vacations with other couples might be fun too (kayaking, sex, gourmet dinners, sex, sightseeing, sex, etc...). We suspect that, if two or more couples all liked each other, it might be fun to go on little vacations together. We're already thinking about inviting a couple on this site (you know who you are) to go kayaking with us, among other things. Are there any other couples out there who have thought about this? Where would you like to go? And if you've already done this, what are your experiences?