Hi I'm the Local Editor for Newcastle/Gateshead.
Well done all of you who have places for the GNR, as the name suggests it's a great run and the locals are fantastic at supporting the event. I've done the GNR 3 times and its a wonderful run to do.
You can park all the way out at Sunderland, but its a city, so city centre parking. On the way going you will get a through metro from Sunderland to Newcastle for the start, but for your return journey from South Shields you will have to change metro at Pelaw or Heworth, to go on a different line heading back out to Sunderland ( basically same direction you've just travelled from South Shields but different line, Sunderland is along the coastline from South Shields)
Tiredemma suggestion of Heworth is very sensible, as there is 2 car parks at Heworth Metro itself, a large long stay behind the station and short stay in front, as well as street parking in the surrounding area. The metros can be busy, but the camaraderie is fun with the other runners and you don't need to worry about knowing which stop to get off at! The metros come from 2 different lines through Heworth, but the metro system also runs extra trains on the day obviously and starts empty ones from Pelaw ( the station just before Heworth)
There is parking at Felling Metro ( small), Gateshead Stadium Metro (street parking) access both Metro stations via Sunderland Road as Felling By Pass ( 184 ) is part of the route used during the run.
On the South Shields line there is parking at Hebburn Metro (street) Jarrow Metro ( street and a car park near by )
Heworth is also close to A1 and A19 roads.
Have a great day, my offspring and I will be supporting you all, they will be the Scouts offering you drinks and I'll be doing the clapping cheering bit 
If there is any local information you want to know nearer the time just post a thread on local chat and I'll try my best to help 