I have to say there aren't many of us out there who are going as just couples, but it is just me and FI getting married! I am sad in a few ways the fam and friends aren't going to be there, but that's why I'm going to go all out with photos so we can bring something special to all our friends and families. One thing we didn't want was to have to entertain everyone while we were enjoying our honeymoon. We can't afford to take too much time off, and by the time everyone would have left, we wouldn't have enough time to truly enjoy time together, as we do so little in everyday life anyway!
Because we're tight on money, also, i would definitely tell you that you should sign up for a honeymoon registry! We used honeymoonwishes.com, and that way it will help contribute to everything, so if you do decide to invite family, hopefully that might help some.
You just have to do what you feel is best, not necessarily for financial reasons, but what you REALLY want! It is, after all, your big day! I hope you decide what's best, and best of luck!