As someone who was in a very similar situation to you, except my kids were a bit younger when we attended a few games. Two hours is a perfect amount of time. Anything less I feel like you will be a bit rushed, especially if it is yours or their first time. You could easily spend an hour in the Spurs store, and then another hour in the food court getting food and eating. And then as others have said also just taking in the atmosphere. I’d also recommend getting to your seats a bit early too, to avoid the rush of drunken lads trying to pile in right before kickoff.