I agree with Jaxter, it just depends on your set of friends. Vacations with friends can bring out sides of them you never knew existed before, just be warned (yes, personal experience talking here!) Make your intentions and itinerary clear from the get-go about when it's 'together' time and 'alone' time--that will help a lot to ease expectations and ideas they might get in their heads.
Considering where you live (I *heart* MT!), a separate vacation for just the two of you later nearby in a cabin or whatever sounds mega-romantic IMHO--maybe you could do that for a ___-month anniversary/honeymoon celebration? If you do that route, make sure you get those plans in place solidly in addition to the honeymoon; otherwise, you may just keep 'not getting around' to it or fidning that you didn't set aside enough money (so it will have to wait over a year or six or whatever). Best of luck for whatever you choose!