A couple of thoughts from me:
1. If you're entering into a partnership with someone, it seems crazy (as well as extremely selfish) not to give as much weight to the feelings of that partner as you do to your own. If you're inviting your own family then it should be obvious that you should invite your fiancé's family too. (As Calmck points out, they don't all have to stay in the same villa though).
2. You ought to consider though whether all of your family/families really want to join you or can afford to do so. There have been quite a lot of press articles over recent years about people who've struggled to keep up with the overseas wedding invitations that they've received. They've often gone only out of a 'sense of duty', rather than as an enjoyable experience.
For example, there have been reports of people who've been invited to attend a couple of family members' weddings in Spain or Greece in the same year that they've also been invited to workmates' weddings in Antigua and Thailand. In every case the bridal couple (or, more often, the bride) has made it clear that there's been a firm expectation upon the invitees that they'll turn up. It's plunged those invitees into thousands of pounds into debt, meant that they've been unable to afford a holiday of their own and left them panicking about the next set of weddings coming up in the following year. So are you SURE that your family (and your fiancé's family) both WANT to attend and can actually AFFORD to do so? (i.e. you ought to be considering THEIR feelings, as well as those of your fiancé).