So are you just wanting to try out less common rolling stock, or are you also interested in the rarer bits of track to travel on?
Annoyingly, the majority of services in the north west and Wales are increasingly run with Sprinter (Class 150/156) and CAF Civity (Class 195/197/331) multiple units, but this doesn’t make the places they run to less any less worth visiting or exploring.
Both of Merseyrail’s classes 507 and 777 are unique, but also being so local you can find yourself wanting to find something further out. It’s a shame that Classes 175, 319 and 508 have gone recently since these offered a bit more variety.
“Parliamentary” services if that is the correct use of the term (which historically refers to something else) such as Ellesmere Port - Helsby or Stockport - Stalybridge which are notable for having only one train a day or one train a week are always interesting and there are quite a few in the north west. One of these is Heald Green North Junction - Heald Green South Junction, that is avoiding both Stockport and Manchester Airport. This is the route which some trains took to Wilsmlow before the Manchester Airport rail link opened and it has been seeing some use this weekend for Pendolino diversions with engineering works at Stockport.
As well as these, one thing I’ve been interested in is going on a certain piece of track on rolling stock that doesn’t normally do it. Engineering diversions can see trains doing all kinds of strange things. The next few weekends for example, all trains between Wigan and Manchester are going via Golborne Junction, meaning they will be using the curve between the West Coast main line and the Liverpool and Manchester Railway, with 158s on some services, but the one Saturday they aren’t doing this, 17 February, the 158s will be getting sent via Bolton instead. Both routes are a good opportunity for them to get up to their 90mph top speed.
I should add, Northern have a small number of 3 car 158s numbered 158752-759 which still the original seats instead of the ironing boards found on 195s and can appear on certain services. So does 158889 with EMR, which can appear on services out of Liverpool Lime Street and this also has a declassified first class area, meaning you can sit in it with a standard class ticket. Class 170 Turbostars can also now appear on EMR services from Lime Street and from Crewe to Stoke-on-Trent and Derby, which are something you might not have seen before.