hello jabbed, We are New Yorkers so not especially intimidated by city traffic because the city is a well laid out grid.
However, Boston has so many older streets and one-way lanes that we find it very hard to drive within the city, so you may want to park and take Uber once there!
The “quietest” route from Laguardia is the Grand Central Parkway to the Triborough Bridge, now called the RF Kennedy Bridge, up towards Connecticut. There’s a bridge toll and tolls along parts of the beginning road, but not worth avoiding…. Anyway, that bridge crossing (scenic views of Manhattan skyline) will put you on I-95 which is a really busy road because all the trucks use it.
We get off I-95 as soon as we can (near Bridgeport, Connecticut) and move over to I-91 which is less busy and more scenic. If you select that route from Google Maps, it will take you into the city of Boston along these quieter roads.
Try to avoid arriving with 25 miles of Boston between 8am and 10am and between 5pm and 7pm, as these are the rush hour for people commuting in from suburbs all around the city. The drive is not dangerous as long as you pay attention, the speed limit is tops 55mph, just ask the kids to help you navigate.
We are sure you will have a fun road trip visiting the Northeast.