Here is a video from someone riding a Los Angeles Metrolink Train. Since our commuter trains will still be running I tried to find a video that showed what it is like to be on one of the trains for those who have more experience.
Some things you will notice about the commuter trains is that they are quieter than TRAX even though they are hold by diesel locomotives. While you will get some swaying once in a while the ride is smoother than riding TRAX.
The Tri-level cars from Bombardier that are used by Metrolink are the same type that UTA has purchased (UTA has also purchased used cars from Chicago and New Jersey) only with different interiors.
This second video is from the Interior of a Metrolink San Bernardino Line train which travels along the San Bernardino Freeway (Interstate 10) from El Monte to Cal State.