Disclaimer: this suggestion has a very personal bias, as usual anything within the blog section represents the view of the author and may not represent the views of Save East Coast Rewards or the other contributors.
Unless you live in Gateshead or South Tyneside you may not have heard of Heworth. It is a bus, Metro and rail interchange located between Felling and Pelaw in the metropolitan borough of Gateshead. Currently with one service a day in each direction between Sunderland and Newcastle there's not much advantage in these services stopping at Heworth and as these services are operated by slam door HST sets it would be impractical stopping there.
The plan when the Azuma fleet is launched is to increase the number of services to Sunderland and the route that Virgin Trains East Coast uses to Sunderland is to go via Newcastle, passing Heworth on the way.
I admit bias because a stop at Heworth would be useful for me but it would also benefit others who live in Gateshead, South Tyneside and even Washington who have better bus connections from Heworth than they do from Newcastle or Sunderland and for those going towards South Shields on the Metro it would be easier to interchange at Heworth than it is at Newcastle.
With shorter dwell times and improved acceleration of the Virgin Azuma I believe a stop at Heworth would have minimal impact on the timetable but would benefit those who live in the nearby area and there is a considerable catchment area served by bus from Heworth and there's also parking and a taxi rank. It would also reduce congestion in Newcastle from people who are currently dropped off at the station by car.
For the passenger I can't see any drawbacks with adding this stop, the improved acceleration should make up for time lost during the stop. There may be pathing issues I'm unaware of though, but I'd hope they'd look into this option.
Currently the only National Rail operator serving Heworth is Northern so it is considered mainly a Metro station but when Transpennine Express used to serve Sunderland it also used to stop at Heworth so there is some precedent on long distance services that pass through stopping there.
It would be a good example of how these new trains can serve communities that the previous ones were unable to.