Exhibitors 18 and younger can enter Youth, Open or both, as long as the shows are not on the same day. So she could enter the Youth shows on one day and the Open shows on the other, if she wanted. If the judges are different, I might consider doing that, but if they'll have the same judges for both, it might be better to just pick one.
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@RabbitsOfTheCreek notes, Youth shows are usually smaller, so not only is there less wait time, but the judges are often more willing and able to take time to really talk to the kids about their animals. Judges are not supposed to know who owns which animal, but even so, the kids often get more detailed comments about their entries as well as others in the class.
The downside is that because the smaller show moves faster, it's easier to miss your class being called. In an ARBA show, the youth exhibitors are required to carry their own rabbits to the judging table, so make sure she pays attention to that.
Hosting clubs often give Youth exhibitors a break on entry fees, so that can be another advantage. Sometimes people expect the competition to be less at a Youth show, but at least where I live, that's not true - many times one or more of the Best in Show, Reserve in Show or Honorable mention awards in our Open shows are taken home by a youth exhibitor, after they won the previous day at the Youth show. (We have our Youth shows on one day and Open on another so the kids can show in both.)
Some advantages of her entering the Open show, on the other hand, include the fact that she'd probably be showing alongside you, so you could help each other get rabbits to the table. She will also most likely have a lot more competition (which is a good thing in terms of the rabbit winning G.CH. legs), as well as see more rabbits evaluated by the judges.
A specialty show is focused on a particular breed, or particular type (e.g. Wool breeds, Rare Breeds, Meat Breeds, etc.). It is an effort to compare "apples to apples," so to speak. An Open ARBA show must take all recognized breeds, and they all compete together for the BIS awards. In general, the same few breeds always seem to come out on top (here it tends to be Satins, Hollands, Polish), leaving the rest of the breeds, which may have far fewer breeders working on them, out in the cold.
So, specialty shows can help rabbits in those breeds get more recognition than they would otherwise, which can give breeders a bump in motivation.
Specialty shows also provide more opportunities for earning G.CH. legs, since Open classes in many breeds are too small for many rabbits to earn a leg. A Creme D'Argent, for example, is a lot more likely to win big in a Rare Breed show than in an All-Breed show, simply because there are just not that many Creme breeders and just not that much stock to work with.
And, if the specialty show is being judged by a different judge that the Open shows, it's another chance to get comments on your animals from yet another source. (You might surprised at how much variation there is among judges in what they see on the table on any given day!)
