Well, since BNS has been announced as one of the main stations in BCC route, I would like to make a suggestion. Class 170, from Nottingham to Birmingham Short route, only about an hour long, but since the NS station is going to be empty, this would definitely add some life into it. A similar suggestion, maybe the 170 from Birmingham to Shrewsbury??? Would make sense to be honest.
I'd like to see a Cross country route, but what about Birmingham - Gloucester with Class 165,170,220 and HST,66,323/Cross City DLC as AI and the British Rail Diesels/Steam as layers for Railtours up the lickey or Drivable Services (Though the HST would likely be for Gloucester-Cheltenham/Ashchurch, unless they Added a Worcester branch). The Trains would also layer onto BCC for fast lines to make it more busy. Though Nottingham - Birmingham would not be bad either.
I would second going South, but I would advocate for going thru Gloucester and then via Lydney and Chepstow down to Severn Tunnel Junction The line would be about 72½ miles long if built from the bottom of the BCC but there's a lot of Gloucestershire countryside with very little going on between Gloucester and Chepstow and going all the way to STJ would allow a link up to any prospective South Wales Mainline route. Stations would be: Worcestershire parkway Ashchurch Cheltenham Spa Gloucester Lydney Chepstow Caldicot Seven Tunnel Junction Landmarks include: Gloucester Cathedral River Severn A lot of rolling hills Severn Bridge (old one) Wye Bridge As well as the 170/1 used by Crosscountry the 170/2 is used by Transport for Wales for runs from Cardiff or Maesteg to Cheltenham, and on the mainline from Bristol upwards there would be a chance of layering in GWR HSTs and 166s on various routes from the South to Cheltenham or Worcester as well as 800s and 220s/221s for GWR and XC if ever these get made
I think there is definitely a need for another route through New Street, if only to make the cross city feel more alive. Hate big stations being empty, just so unrealistic.