While Artscroll's Shottenstein edition of Shas might be their most famous work, their siddurim and machazorim probably touch more people's lives
Formal study of Jewish Liturgy is not common, but it is highly under-rated. Our prayers are not only about communing with the All-Mighty, it is also a repository of normative beliefs and hashqafot.
As such, knowing the liturgical cycle will teach more about accepted Perspectives than say En Yaaqov or Midrashim. Ironically many piyyutim are founded upon those very texts, Talmudic and Midrashic Aggadah.
Examples, think of the dozens of S'lichot known as "Aqeidah" for examples of poetically mining numerous aggadot on a single subject.
At first I perceived a 6-8 year course of study. Now I am reconsidering that time-table and restructuring this as modules instead.
Simply cover the standard Artscroll Siddur "cover-to-cover".
In addition to liturgical insights one will learn
1. Simplified Hilchot Tefillah
2. 7 chapters or Mishna
• Avot 5 chapters
• Shabbat ch 2
• Zevachim ch. 5
3. 2 chapters of Braittot
• Avot ch. 6 from Kallah
• Braitto de R. Yishmael
4. Selected Piyyutim and Selichot
5. Selections of Torah Readings
Using Artscroll's "Siddur Nechemat Yisra'el"
This will supplement the regular Daily-Shabbat siddur with
1. Basic minhaggim of Aveilut
2. Many more Mishnayyot
3. Various Prayers for the cemetery and Yahrtzeits, etc.