I am thinking of taking the Amtrak Coast Starlight train from San Jose to Portland.
How safe and comfortable is going in the coach class? Affordable sleeper class tickets are unavailable for my journey date. I will be journeying alone and have never journeyed in Amtrak before.
Is it advisable to leave my belongings at my seat, while I go for meals or to the lounge? If not, what options do I have?

Any tips that will make my journey better?

Thanks