Rehearsal Dinner

My son is getting married in a location where everyone is coming from out of town. I looked up wedding ettiquete in regard to who should be invited. In addition to the wedding party, It mentioned that you can invite other relatives and out of towners. Since everyone is an out of towner, some relatives are coming from 1hour, 2 hour, and even 4 hours drives to attend the wedding. I decided that the only relatives that I would include in the rehearsal dinner are the ones that are flying to the wedding. I feel that this would be a nice gesture since they are incurring more expenses to attend. The problem is that all the relatives that are flying in are from the husbands family only. My wife has one sister who is driving in from 2 hours away and my wife feels that this is wrong. If I change that distinction as to whom to invite, than I open it up to others that should be invited from the brides side of the family who are driving in also. Should I not invite my relatives to the rehearsal dinner because it would cause hard feelings?