You've already decided who gets a plus-one to the wedding, and your bridesmaids and groomsmen all made the cut (of course). But your wedding party is attending a lot more than just the wedding, so should their dates be invited too?
When you're making the guest list for your rehearsal dinner, the only people you need to invite are those who are participating in your rehearsal, which probably includes your immediate family, your wedding party, and any friends or family members who are doing readings as part of your ceremony. Inviting anyone beyond that is a nice touch, but isn't required.
But if you're planning to invite additional people to join you at the rehearsal dinner, the dates and plus-ones of anyone who is participating in the ceremony should be the first people you add to the list—including your wedding party, siblings, and other family members. Since you're inviting the wedding party along with their dates to your wedding (whether married, dating, or just friends) that means they'll probably be in town the night before too. Avoid the awkward situation that would leave your bridesmaids' boyfriends and partners to fend for themselves for dinner (as well as any resentment from your bridesmaids) by including everyone in the dinner plans.
You don't, however, have to invite them to the rehearsal itself. Having additional people hanging around can be distracting and might prevent your rehearsal from running smoothly and quickly, so ask all the plus-ones to meet up with you at the restaurant, once the logistics are taken care of and you're ready to start celebrating.