Here area number of thoughts I have on this past Rosh Hashana.
1. It amazes me how people waltz in to shul late on Rosh Hashana. Yes, davening is earlier then a regular Shabbos, but still how hard is it to get to shul on time? I had a Rebbe in 9th grade, R' Yitzchak Cohen, who I still remember very well 25+ years later for his musar. One of the things I remember very clearly is how he exhorted us to come to to shul on Rosh Hashana on time. He gave the following reasons:
a. Imagine if you had a secular court case and the trial started at 9AM. You would not dream of waltzing in at 9:20AM, you would be too afraid to come late. You would make sure that you got there on time if not a few minutes early just to be sure. Forget about court cases, imagine if you had an important meeting at work, would you show up late 20 minutes late? Rosh Hashana is the Yom Hadin, we are all on trial for our lives. To come late to shul shows that we don't really believe it and don't take it seriously.
b. Rosh Hashana is supposed to be a day where we daven with extra כוונא. To come late and have to hurry through or skip parts of פסוקי דזמרא kills your כוונא and again shows what is really important.
2. The acharonim point out that although on Rosh Hashana there is no issur of fasting half a day and therefore davening should go a little past חצות, that is on a weekday. However, on Shabbos the issur of fasting applies and therefore you should try to finish before חצות. This din seems to have fallen by the wayside. Very few shuls seem to be makpid on this. I remember R' Willig telling us in shiur, that when Rosh Hashana fell out on Shabbos he would tell his Baal Habatim that he would compromise with them, he wouldn't speak and they would start 15 minutes earlier to finish before chatzos.
3. A long speech by the Rabbi is counterproductive on Rosh Hashana. People are in shul for 5-6 hours, they are simply not able to sit and listen to a speech by the Rabbi for a half an hour. If the Rabbi feels the need to speak he should keep it short and simple.
4. Announcing how long the silent shemoneh esrei is going to be (15 minutes, a half an hour, whatever it is) is a tremendous help for kavana. This way people know how long they have to daven and how long they have to wait after they finish. You don't have people fidgeting and trying to figure out when is the chazan going to start chazaras hashatz and people who want to daven a long shemoneh esrei know exactly how long they have.