Every major cinema I know of in San Francisco allows seats to be reserved on a first come first serve basis. All seats cost the same. It’s extremely simple, and while there might be some negative effect for the cinema whereby people won’t buy tickets for a showing if they see all the good seats are taken, but I strongly suspect that is far overwhelmed by the effect of people going to the cinema more often because they know they won’t have to show up early or worry about getting decent seats.