I used Kawhi off the bench for a while before I unlocked better players to replace him with. He can hit the three consistently (he has a good release point, or at least he does to me) and he's a good athletic defender. I was using him to guard guys like LeBron and KD when I went up against them. When he's at the SF with Paul George at SG they're a scary defensive mid court.
Marcin Gortat is probably the worst Gold player you can unlock. I would say feel relieved when you do get him, but we all know how they love to dump a crummy duplicate in your lap when you're hoping for someone else.