Have you ever been to a really good theatrical performance, where at some point, everyone in the theater is totally united in their attention to and involvement in what’s happening on stage? It’s where the “artistic” crosses over into the “spiritual.” That’s “group cohesion.” In my mind, “group cohesion” is what makes a service become “a service,” rather than just “a meeting.” 
      I try to provide content that I myself am satisfied with, too, for which I credit primarily Maharishi Mahesh Yogi and Rabbi Morris Lichtenstein, who gave me well-laid out, systematic ideas to work from. 
     I’ve also made the effort over many years to learn how to do it. In the beginning, 20 years ago, I remember giving a talk where people were walking out on me. But (and it’s so unlike me), I knew I had to just keep trying.
     I’ve also been very willing to vary a service, without letting it feel insubstantial. For example: On “Sukkot” (or “Tabernacles,” as it’s usually called in an “English” bible), one of the observances is to wave a lulav (palm branch), with branches from a Willow and a Myrtle tree, while holding an etrog (a fruit that looks like a lemon on the outside, but isn’t). I did it at one Erev (evening) Sukkot service, although it’s usually done in the morning, because I knew that there’d be people there who wouldn’t otherwise have a chance to do it. I prepared a “meditation guide” handout, which helped the people find further meaning in the act they were doing. Each person got a copy of the handout to take home. I got very positive comments afterwards.
       But even the variations depend on the congregation. Even before the service, if possible, I try to “feel out” the group. Not everyone in the group is the same, of course, but groups have a collective “personality.” I find that if I address myself to that, most of the people will feel included. I might introduce various prayers with an explanatory quote. This allows me to “explain,” without necessarily interrupting the flow of the prayers themselves. With one group, for example, I made sure to introduce each quotation or reading by the rabbi’s name: “Rabbi so-and-so said…” This gave them the feeling that they were receiving the knowledge from a tradition, rather than from me personally. For another group, with less interest in tradition, I provided many of the same quotes, but without mentioning as many of the rabbis. This let them focus on the ideas in a way that was more familiar to them (i.e. short quotations).   
      So, I try to create a service with “substance” and “group cohesion.” The latter also involves a sense of “flow” — it should become something that people relax into and forget themselves, like a concert or a play. At the same time, I have the option of varying how the prayers are done, by doing responsive readings, silent readings, whole-group readings; by chanting (rather than reciting) some of the text in English; etc. 
     I’ve often woken up the morning after a service with a really happy, satisfied feeling. I think that I was affected in a positive way by my own service — which is how it should be. Whatever the forms and details, a “service” is essentially a personal prayer and/or meditation, in which we meet with G-d’s Presence in and around us.  
     So: liturgy can and should serve as a “framework” to produce group cohesion via a spiritual experience that all (including the clergy) share collectively. People should go away feeling “changed.”
      Of course, it’s probable, even typical, that not everyone who attends a given service will feel the same way. People come in with different needs and different expectations.  But that’s OK.