Tomorrow night, at First Vespers of the Feast of the Holy Trinity, we switch Marian antiphons, from Easter's Regina caeli to the Salve regina. Everyone knows the simple Salve, but I encourage as many as possible to get to know the solemn version as well, which can be found in the Antiphonale.
Also, you might wish to make a special effort to sing the Regina caeli at noon, since it will be the last chance until next March.