Thunderton (Thunderdome/Thunderbum etc etc) is under new management and isn't as good as it used to be. They will be serving lunches pre match, so expect a family atmosphere where more people will be there to eat rather than drink.
The Granary is about 20 yards away from the Thunderton and is indeed a chain pub. Again at that time of the day it will be families in here having lunch and like the Smith and Jones pub is overpriced and devoid of character.
I'm still dithering on whether to head through, but the pubs I'd visit would be the Wetherspoons (Muckle Cross) as it's cheap and has a good choice of continental and local ales. Note* stay away from the Ionic across the road...
I'd then either head straight to the Elgin City Social club in the stadium or have a quick visit to the White Horse on the high street for a game of darts, pool and £1 in the surprisingly good jukebox. The Vic is also good for real ales usually, so that'd be a post match visit; before heading to home.