1. Invite your friends that get along with your family
The truth of the matter is, some friends might get along with your family while others might not. It's not necessarily a bad thing, it's just a matter of being on the same wavelength. To avoid the awkwardness, you could have a get-together like dinner or a day out before planning the trip to gauge everyone's comfort levels. Once you are certain of the chemistry, have a discussion with your family to see if they would be comfortable with your friends joining the family vacation. Only once everything is aligned with your family members can you proceed to invite your friends. If you and your friends have kids, this getaway could be an opportunity for the kids to really get to know each other.