I'm a big fan of the laity but I want to see training in giving sermons and have those sermons go beyond the standard works and the Ensign. Give up to 1 month for lay members to prepare a sermon where they can research and find sources from across history and around the world. And then keep sacrament meeting to 45 minutes-ish since just the administration of the sacrament takes 20.
However, the administration of the sacrament can/should move to the jurisdiction of the family. Those who want to/need the church for the administration of it, can attend that portion of the meeting, but its ridiculousness to be that the church actively precludes people from taking the sacrament if they can't make church due to not-deigned-to-be-good enough reasons.
After sacrament, the children should be able to leave the chapel and go to their classes. The Unitarians in my home congregation do a cool thing where they sing the children to their classes.
Music in sacrament yes, forget the staid and move in with the joyful, exuberant arrangements. Dance and sing, move and clap. Musical instruments of all sorts performed by ward members.
Joint priesthood and Relief Society, ordain women, make this meeting after sacrament and keep it to 45 minutes. Sometimes have this meeting about action, or use it to brainstorm advocacy efforts and how their ward can put the gospel into action in their community. Knit during meetings, cut out file folder games, etc.
Sunday school last (and maybe not on Sundays), have it for those who want/need to attend. Maybe even give over the Sunday school to the Institutes, encourage each member to be attending one class at all times, call seminary enough for the YM/YW and build it into their programs to earn their achievements.
If not a potluck something like a "coffee hour" where drinks and maybe sometimes snacks are served. Church at this point is only 1 1/2-2 hrs so you shouldn't be having horribly hungry people. Obviously find a different name "fellowship hall" or "social hour." Give people a chance to visit, discuss and really get to know the goings-on of members of their ward. This is where the throughout the week fellowship is going to be strengthened.
I also think that if church on Sundays wasn't such a major investment, members would be more willing to do social/volunteer/nature stuff outside of church. I love the ideas of sometimes conducting worship services outside in nature. That would be a good use for the church owned recreational areas a few times a year.
My thoughts are pretty influenced by the Unitarian Universalist ways of doing things. For a few years now, I have been missing a good, well-prepared, profound sermon. Not having the children in the meeting for the sermon is actually more conducive to worship and for mature reflection. After a coming of age, perhaps 12, the youth can be made apart of those sermons as well. I miss those coffee hours where people visit and talk before leaving to go home.
So those are my ideas, anything here you know you wouldn't like? What is your ideal church meeting?