Today, I'm going to propose the Sheffield to Hull Line as far as Doncaster (via Goole). There's a good variety of services, including stopping, semi-fast and express. Services on this line are operated by Northern, TransPennine Express, Hull Trains and LNER (the latter three via Selby). This part of the route leaves the main line at Gilberdyke (which continues via Selby towards Leeds, York and Doncaster). It then goes along the Goole branch, joining the Cleethorpes line west of Thorne. Major stations: Hull Paragon Interchange - a major interchange and eastern terminus of this route. There are six platforms numbered 2 - 7, as well as Platform 1 which will be in use as of this year. In March, the buffers on Platforms 6 and 7 will also be brought into line with the others. Brough - the first major stop along the route, serving the town of Brough. Goole - one of two stations on this branch (the other being Saltmarshe). Doncaster - the western terminus (the actual line continues to Sheffield. This route will include the Class 170 (3-car) as the new train, and the 158 (2-car) can be reused from Midland Main Line (with a reskin). The 802/3 Hull Trains and 185 TransPennine Express will not appear, mainly because their services stop at Brough and go via Selby. The 801 from ECML can layer at Doncaster. The 170s work the Hull to Sheffield (from Scarborough) and Hull to York (from Bridlington) services, the Sheffield one going via Goole with one per day via Selby. The Class 158s run the Doncaster stopping service and the Halifax services. The Halifax services only stop at Brough before going via Selby. I believe this route would be a good one, as there are plenty of services. The 150/2 (with updated sounds and reskin) can layer from WCL and do the occasional Halifax/Doncaster service, replacing the 158s. The 155 could come as a DLC substituting for the Halifax and York services, as well as static at Hull to go to Bridlington. I know the 158 and 170, as well as Hull station, inside out, and will be more than happy to get reference material if this route were to be. I probably missed something, so please tell me.
One thing I forgot to mention is the depot. Hull Botanic Gardens depot is a short way to the east of Hull Station Most trains only come here for fuelling (scenario idea maybe), but they have some stay overnight (for various reasons).
Given a 170 is confirmed for Fife Circle, time to resurrect this suggestion. The 170s on this line have ScotRail branding, so they only need to be painted into Northern livery (unless there's interior differences I'm unaware of).
The asphalt terminal could also be included to bring in freight runs along the line. Also, there is the Seimens plant and docks in Goole providing an opportunity for ECS and freight runs. Also not forgetting one of the best scenic views from a train journey, travelling next to the Humber and then under the Humber Bridge.