I would put us at the more extreme end.
We have 3 kids, 17, 15, 11 (none with a licenses...but that for a different generational discussion time). We have had a Leaf for a little over 6 years (2013 SV and then 2019 SV Plus). Since getting our first Leaf we started moving most of the driving off of our old minivan (2007 Sedona with about 60K miles) to the Leaf.
In the 2013 Leaf we would do any family travel in the Leaf. Our youngest started out in a car seat in the back of the 13, but obviously no need now. We continued to take road trips in the Van though for obvious reasons until we bought the Plus. We have done with family 2 car seats, but never had the need for 3. I have seen online 3 done though, but you might want to pick the brand based on size as well. If the kids are in the booster stage, and you have a mid size car or smaller with 3 in the back, buy a "bubble bum". Its a few inches narrower then the hard plastic seats and is easy to pack for air travel. The leg room in the back is pretty good, and if my wife liked to drive, I honestly prefer to sit in the back of the new leaf giving one of teens the front, as it is quite comfortable (I am 6' 2" for reference). I know some taller folk touch their heads on the ceiling in the back, but my proportions haven't had an issue.
Now with the 2019, I have started taking the kids on longer hauls for some college visits. We did one (from Chicagoland) across Iowa, One to Wisconsin, and one to IU in southern Indiana. Chicago Land to Iowa City and Chicagoland to Bloomington IN were both on single chargers on the highway. For the longer hauls, its important to have Leafspy and watch driving efficiency. With just the dash gauge, I would keep single legs to 200-210 miles, but that is still 3 solid hours of open driving, or 4 if you have traffic (as we often do around the city/border). We did Chicago - Waukesha - Chicago in 1 charge with plenty to ride around town and over 25% reserve, so being able to to that kind of day trip is fantastic. (again, driving style and weather may affect individual results) . Those runs are just with 4 of us. The wife enjoys the breaks while I take the kids for the college visits.
For running around town, we still use the Leaf exclusively, unless a schedule conflict forces us to use the old van. No one wants to drive it any more. We just put all 3 kids in the back. My teens know if they want to sit in front or not always sit 3 across, they can get a job and buy a car.....ha...but I digress. For 15-20 minute rides, it works for all 5 of us. I don't know that we would go beyond Milwaukee area with all of us in the car just because the kids are bigger now. When they were younger, putting the 3 across wasn't an issue. They just fight more now.
The Niro and Tesla 3 have similar sizing in the back, so you could look at the other options as well. The Tesla was quite a bit more expensive (this was our first 30K car - post rebates, and Wife had not interest in a Tesla, especially for the extra 10K...Niro is not coming to the midwest anytime soon).
I haven't noticed any significant range impacts to having 4 or 5 passengers vs. 2 in the new Plus, which I did notice in our 2013.
Hope this is of help.