As an experiment, I tried making it a 2-sided game. By that I mean rather than one side serving all the time, I ran it more like a regular game situation with each rally deciding which team serves the next ball. So basically what you have is a game that gives bonus points based on the quality of the serve.
Here’s the wrinkle, though.
Rather than having the rally winner serve, I had the loser serve. In other words, winning the rally gives you the right to receive serve and thereby gain more points from good passes.
So far the players seem to like the game, though the loser serving bit is a bit confusing at first. If you play to 25 points things will tend to go fairly quickly. That’s good if you want to play several games, mix things up, etc. If you want longer games, though, you can play to more points or maybe only give points for high quality passes (say 1 point for a 2 pass and 2 points for a 3 pass, or just 1 point for a 3 pass). You could even think about using negative points for things like overpasses of whatever you might want to focus on.