I think it would be more useful to have additional trains over the existing routes before adding more routes to the network. One wonders just how much more ridership there would be if there simply were more trains along a given route. The other thing I would add to the list would be upgrading the tracks through Madison, WI, and then sending the Builder through Madison -- though I would have to figure out some way of getting the funding past WI State Legislature members of a certain party.
Adding additional daily LD trains over the existing western routes would require a lot more from the annual operating subsidy. Just not going to happen in the near term (which I mean 5-10 years). LD expansions that have a good chance are a daily Cardinal, maybe a restored Three Rivers/BL if the Pennsylvanian to Capitol Limited run-through cars are a success, perhaps a daily Sunset Limited after UP finishes double tracking LA to El Paso, and maybe some NYP to FL expansion. It will take a major political push by the states on the route to restore the SL route east of New Orleans.
The more viable approach to "double" up LD routes is state supported corridor service over a portion of the route. The Virginia Regional Lynchburger is the prime example of this. The criteria should be large enough cities to support it, competitive trip times over the route, and less than a circa 12 hour route.
In California, looks like the Coast Daylight from San Francisco to LA is going to happen in 3-4 years. California is also studying a LA to Coachella Valley/Palms Springs corridor service. The prospects of a twice daily corridor service over that route are more tentative, but CA has money for passenger rail and a production line starting up for corridor bi-level cars.
In the Midwest, Minnesota may be willing to fund a Chicago to Twin Cities corridor service. They will have a nice new station with a new light rail line connected to it in the next several years. Any money they put into track and capacity upgrades on the route in MN and WI will also benefit the EB.
Another Midwest route that is viable is a Chicago to Cleveland daily corridor service. The western end is getting upgrades in Chicago and Indiana. But the current political leadership in Ohio makes it pretty hostile territory for state supported passenger rail for the time being.
If Florida, the FEC and All Aboard Florida can work out a deal for a Jacksonville to Miami corridor service - whether it is run by Amtrak or not - that should open the FEC for a Silver Star split at Jacksonville with a fast route to Miami.
There are other possible corridor services over portions of LD train routes, which have been discussed here many times. And will be again. But they have to have a state government that is willing to fund the service in annual operating subsidy and track improvements. That puts some states into the No category for now such as OH, IN, GA, SC, Arizona.
BTW, the February 2013 Monthly report has been posted. Amtrak is getting the MPR's out sooner. Someone here may want to post a summary...