I have written in the past about spending time alone in the abbey church before the monks come in for the Divine Office.
Oddly enough, the few unusual things I have experienced in church happen in those alone times before the Divine Office — in that time of preparation — not during the mass or the Divine Office.
For example, I remember one afternoon before 5:00 pm Vespers (part of the daily Divine Office), when I had a fraction-of-a-second, but very strong sense that several of the saints were present. I know that others have similar experiences, but I thought such encounters were most often the results of prayer — not part of what prepares one’s mind for prayer. Regardless of whether my relaxing mind missed a shift and went into the wrong gear for a second, reading and rereading “Saint John Cassian on Prayer” has caused prayer-preparation to be on my mind for some time now — no matter who else is around!