Drawbacks are that if you are older like me, the seats are not sleeper friendly. There is the possibility of kids running up and down the isles, but porters try to keep that under control. The sleeping car is preferable, however it is more expensive, but the price does include meals, so consider that . Amtrak reccommends that if you are a light sleeper, you might want to take earplugs and eyeshades. If you are taking a baby who drinks formula, bringing your own water will help prevent the baby's system from getting upset due to the change in water.
Many stops have vendors that sell food items at stations where longer stops are made.
There are no places on the train to get cash. Guard your valuables and put them in a place where they are protected. We put all the keys on 2 key chains in case 1 set got lost. Take a pillow , as theirs are a joke. I took wheat grain pillows.