It's not everyone's favorite part of the wedding process, but alas, it must be done - rehearsals are a customary practice to prevent goof-ups on the big day, and it's often a chance for the wedding party to bond with each other prior to the event.
You may be swamped with preparations, but offering guests a token of appreciation for sticking through the process with you won't take too much of your time and money, and it will make attending the rehearsal dinner a bit more appealing for those who are counting down the hours until they can hit the open bar at your reception.
Personalized wedding gum favors and wedding personalized lollipops will help guests pass the time in the sweetest way possible. Custom label bottled water may be an even better idea, since a few hours of practice time would make anyone thirsty.
Bridal party buttons may also be appropriate to promote the spirit of sisterhood that's behind every great wedding, and custom fortune cookies will surely be adored by all guests.