I've created a rideshare / roomshare Google sheet. 

https://docs.google.com/spreadsheets/d/1vvySC8b7ZVkEjnIYbHflYp96QFxWmSV6VHBBxm9-WYk/edit?usp=sharing

For arriving from EWR, you can take New Jersey transit to Princeton Junction or Princeton. If you''re staying in a US1 hotel, you'll want to get off at Princeton Junction and rideshare, which is always nicer with a friend. 

If arriving on Sunday sharing a ride may be faster and more convenient. I'd advise against doing that on monday morning as rush hour traffic can add a half hour to the trip and there are plenty of trains.

If staying in Princeton (the Graduate or the Nassau Inn, take the Dinky to Princeton and walk 15 minutes or rideshare/taxi the rest of the way.

The US 1 hotels are in clusters, so sharing rides can be very useful, even if you have a car. You can create messaging groups for more spontaneous organization.

Eric