The Q: "I'm confused. I'm having my ceremony and reception on the same site and there is no time the day before to have a rehearsal. What is the point of a rehearsal dinner if there is no rehearsal? My FI feels like we are expected to do this, but it seems silly. Do we need to have one?"
The A: Totally get your confusion. Rehearsal dinners are not necessary, especially if there isn't a rehearsal. However, there is something really nice about this intimate gathering without all the pressures of your reception the evening before your big day. It's a great forum to work out a lot of the emotions that everyone is carrying around so that you aren't as overwhelmed by them on the day itself. It's also a great opportunity for your families and friends to connect, and often facilitates a smoother day on the day itself.
However, they can be annoying to plan, or tedious if you are trying to plan that as well as the wedding.
When there is not a rehearsal, I tend to not call these rehearsal dinners, but rather "Dinner the Night Before" and I usually suggest that our clients address them as such on any printed invitation that they may send out so that people aren't wondering when and where the actual rehearsing is going to take place.
Sometimes, if the pressure of planning or the expense of planning seems to much for you, I suggest that rather than a full dinner, you do a family dinner with both sides of the family and then invite your out of town guests/ bridal party to gather at a bar, lounge or hotel suite for cocktails and mixing.