According to Musicam sacram, the first, most important, degree of solemnity is the chanting of the priest - in dialogue with the congregation and in the various prayers of the presider alone (the Collects, the Preface, etc.).
While more and more priests are taking up the singing of the dialogues such as "The Lord be with you" (and hearing back a typically hearty "And with your spirit"), many still find the singing of the proper weekly prayers a bit difficult.
Part of the difficulty is that the texts of these in the English translation of the Roman Missal are not provided with musical notation. A priest who wants to sing these has to be comfortable with the melody (the Simple Tone or the Solemn Tone) and then know how to apply it, more-or-less on the fly, to the text of the prayer.
While it is certainly admirable for a priest to have this skill, it is not something everyone is able to do. But that's okay.
Thanks to the wonderful work of Anthony DiCello, director of music at Mount St. Mary's Seminary in Ohio, priests now have a resource of fully-notated chants for the opening collect, the prayer over the gifts, and the prayer after communion. These are available in both the Simple and the Solemn Tone.
These resources are notated in modern stemless round notes and are easy to read and work with. They can be found in the Liturgical Resources section of the Mount St. Mary's website.