I know that immediate family, bridal party, and out of town guests are generally invited to the rehearsal dinner.
Actually, this is social-circle specific, and if you read it in an etiquette book, it's probably from a time when few people traveled very far for weddings.
Now that travel is cheaper, families spread out more, and women especially leave their parents homes and live elsewhere far more than they used to, this is not actually a "generally" that you can count on.
You know whether your social circle expects it, but even if they do, you aren't required to do it.
The people who -are- invited to the rehearsal dinner are the people who are at the rehearsal and their social partners (spouses, boyfriends, parents in the case of a flower girl; sometimes kids if you want).
I personally think it's just too much to try have another huge gathering, right before the big event. I wish the whole "entertain the out-of-town guests!" thing would go away.
I get that it's gracious, and that people (MOB, MOG, B&G) may feel they've invited people from far away and then abandoned them. But really, grownups can entertain themselves. And it's just becoming a huge burden.
If you are
going to invite "out of town guests," that means "people who are staying in a hotel the night before the wedding." 2.5 hours, they're probably driving over the day-of; don't burden them with an invitation for yet another night too. They'll feel they're obligated, or deeply wanted, and they're already going to have to travel the next day. Let them stay home and feed the dog.
Because, you haven't uprooted them from their home for the event, leaving them in a strange town with nothing to do, and all the people they might want to spend time with being occupied at the rehearsal dinner. THAT is the reason you invite people from out of town.
Invitations should be specific and detailed; they should be issued by whoever is determined to "host," no matter who is actually writing the check.