I disagree with the idea of doing single rider for them. First of all, I'm pretty sure they have to be 8 to ride alone. Second, RnR is pretty wild...it's dark, it flips, and it has a launch like something they probably haven't experienced. Not trying to scare you, it's my favorite ride in WDW. But it's not a kiddie coaster. I would get a FP+ for that and go ride with them.
Toy Story is a ride where you sit in a 2 person cart with a pop gun in front of you, activated by a pull string. You are taken to different rooms with large screens in front of you and you have to "shoot" targets. For example, one of them is ring toss...you aim and pull the string and it tosses rings at objects. It's awesome...our family is very competitive. We come out of that ride with our arms tired from pulling the string so fast.
I can only imagine triplets. We have a 12 year old and then twins that are now 9. Having twins was an amazing experience, I can't imagine adding a third to the mix, especially when they were babies.