I will look forward to discussing this subject more tonight, but a couple of quick thoughts ...
* I assume that we're talking about travel ball here, but I think we need to define what is meant by utility players. When we talk about the Indians, that's a whole different story ... first of all we're talking about a roster of 25 players and there we have true position utility players who are still paid lots of money to fill in when and where needed. To Lou's point, you do need to get them in often enough to keep from getting rusty, and that's about all you owe them and the team. On a travel team of 11-12 players, everyone should play "a lot".
* I assume the question might be better stated how often should your "bench" players play in youth travel ball ... and I am defining bench players here to mean those players who aren't usually in the starting lineup when you're in a championship game late on Sunday. It's not a matter of keeping them from getting rusty, it's a matter of developing them into better players, not to mention a matter of keeping them and their parents happy for the time and money they've committed to the team.
* It's very important in this scenario to use the pool game formats to get everyone starts, and to get most of your roster into every game possible. And it's also important that you at least find spot starts and sub opportunities to get them into elimination games as well. My general rule of thumb was that no travel position player (excluding strict pitchers here) should be playing less than 50% of a team's innings or getting less than 50% of the at bats as the top players. It's my role as a coach to ensure everyone is developing and getting playing time, while putting the team in a position to win most games.
It's a tough balancing act, and I will admit that it's extremely difficult to keep everyone, especially parents, happy. It's not that most parents expect equal playing time for all, but instead that it's their DD who should be in the lineup when you're playing championship/elimination games.