1. Improved customer service, as Neroden expounded on. Not "white glove" Lucius Beebee, stuff, but fundamentals, like timetables, agents that know what they are talking about, on-board staff that doesn't make up restrictive rules on the fly for their convenience, etc.
2. Increased frequency of service on most routes.
3. Either totally eliminate dynamic pricing ("buckets") or narrow the range between the lowest and highest bucket. Amtrak's goal should be maximizing ridership and getting people out of their cars, not managing scarcity by raising fares. To maintain revenue, they'll need to obtain more rolling stock to be able to handle rush periods without selling out. They really should be aiming to make passenger rail, at least in the corridor markets, a major player in transportation mode share along the route. The average American should know that taking a train is a viable transportation option in much of the country.