Thanks for this very useful feedback, responses below:
Thanks for setting this up, booked again today (avoiding Uber's 10% back promo on paypal+!) as your seat selector is better even than LNER's (which doesn't support individual seat picking on Grand Central). GC tickets are so cheap and compulsory reservation so an extra ticket can be a great way to get more legroom, as long as the seats line up! Interesting to see your site also offer a Durham - Knottingley advance ticket that I couldn't get LNER to show, regardless of changing via / avoids - LNER were happy to sell more expensive tickets on slower services instead.
Speaking of pickiness

there were a few quirks you may (or may not!) want to look at...
The seat selector somehow renders this as a bendy train with some surprising gaps... still nicer than Grand Central's own train layout which used that graphical design program Excel! Note it promises the ability to show me which seats have window views (none apparently), and whilst its obvious to us what the grey rectangle is others may struggle.
Can I ask you to scroll down and use the built-in feedback mechanism so we can pick this up? We have a reliance today on the data the operators maintain, which is usually of a poor quality. However, if you let us know via the feedback dialog it'll send useful information to us that enables identifying the service.
All the seats selected are apparently window seats after all, rather than table window/aisle!
Again, if you can use the feedback dialog we can check what attributes are set on the seats in the reservation system and override it/escalate when we see that it's wrong.
It's not clear what an unreserved coach is, or why it matters - it sounds like nothing is currently reserved and therefore plenty of choice. Maybe 'unreservable' would be clearer? Though I can select seats (which errors out when saving on Cross Country, but works on LNER) and of course it shows some seats are reserved.
"Unreserved" is the term that TOCs appear to use, as opposed to unreservable.
Some TOCs don't seem to consistently prevent reservations in the coaches that they have described elsewhere as "unreserved", or have very complex undocumented rules that open up reservations closer to travel or if other coaches fill up and the moon is in the waning gibbous phase. It is difficult to know if we will be able to make those reservations ahead of time without knowledge of this business logic.
Not sure what the point of this message is - I feel bad as I'm not a business and missing out. It implies I can click something to be a business and extend the stated time.
You should not be seeing this message; it's for business customers who have an extended basket duration configured on their account. There is a bug in the backend which means the frontend isn't given enough information to correctly determine whether this should be shown or not, unfortunately. Sorting it out is on the backlog.
I'm unclear what Raileasy is or why it matters
Raileasy is the Merchant of Record (MoR) that takes money off customers and fulfils orders.
clicking the link takes me to Trainsplit's T&Cs (another name that doesn't appear when I go
https://tickets.railforums.co.uk/)
I would not say I have a great understanding of Raileasy's branding strategy.
The forum site I think has described itself in the past as "Powered by TrainSplit", and the About page on RailUK Forums's site references TrainSplit.
Very much a personal preference, but a group booking delivered individual Apple Pay tickets which stops you swiping between them when being inspected. Will be interesting to see when the apple pay tickets appear and disappear from my home screen and active wallet - LNER have had all sorts of problems with theirs, there was a long-running bug which made them appear a day early (and scare you!), then they would disappear and archive themselves when the train arrived (great idea, unless you're walking through a barrier 2 minutes later and need to scan!) and currently they're still showing in my active pile a few weeks after travel.
Yeah, this has come up before and I think there's a ticket in the backlog to look at combined links for groups to enable this, but people's approach to group travel does vary. Some prefer to distribute the "Add to wallet" links to group members so they don't have to travel together and can traverse the gateline independently. Other people would prefer to have one person responsible for tickets who can scan everyone through.