Running Greater Manchester Marathon next weekend. I might have some work to do on the train so it would make sense for me to nab a table with a socket. Quite fancy a first upgrade so I can spread work out a bit. Thing is, I've got a pair of Advances from Grimsby, split at Sheffield. I'm guessing that I could only upgrade one of those for my fee, right? So if I upgrade from GMB I'll have to return to standard for the Hope Valley, which in my experience, is the busy bit! That said, I do have a reservation in Standard for that... Or can I even upgrade an STD Advance to Weekend First? Apart from universal availability of power and a compartment that if I'm unlucky I'll have to share with one other person, is there any other advantage to upgrading on that route?