There’s a Trello Card on the Gameplay and Studio Features board for an orientation indicator for seats/spawns, but it was moved to unpopular. Knowing seat/spawn orientation is important because you want to make sure they’re facing the right direction and in the case of seats, players don’t clip into something upside down because the top face of the seat was pointing downwards, so with the future for the feature not looking so bright, I went ahead and took a couple minutes to make a plugin to accomplish the same thing. Whenever you select a spawn or seat (including vehicleseats), you get two orientation markers on the selected object. The green arrow denotes the top face, and the yellow pole marks the front face.
Left to right: part, spawn, seat, vehicleseat:
You can install the plugin here