Done RS many times (and SO EXCITED we're nearing the end after 14 years, although still not completely done yet.) We would sometimes try to do a ride nearby, but it sometimes it was hard to find something nearby that either didn't then have the other party waiting too long or that we wouldn't go on later as a family that the little one would want to ride multiple times. In our case, our entire family would do the Living with the Land boat ride, so I wouldn't bother to take my 2 year old on it again. Something like EasyWDW (I'm sure there are others) will give a "average experience time" for attractions. For Soarin, it says to expect with Fastpass that the total ride time would take 30 minutes. Your right in between The Seas and Imagination. I would wander to one of the two Pavillions and do the things there that aren't rides. Journey into Imagination has an interactive after ride area that my kids loved when they were little (I think we can just directly enter this area.) The Seas will have exhibits to look at and they can climb on the large shark, etc. We also did Character Meets if one was nearby, and got snacks and did plenty of shopping while waiting too. Some rides, like Mission Space, have a little play area in the attraction.
My in general advice would be any time you can find something non-ride near them to do, do that. We're taken 3 kids all when they were 2, and although they all did great on their trips they would just get tired of waiting and sitting and riding. They would just need "run around time." So if there was a fountain nearby, a play area like above, anything like that where they could just kind of run free and explore that was always my first choice.