One major difference in liturgical style between Catholics and Evangelicals is the Lectionary. Both of us rely on "expository preaching," which means that we base our sermons/homilies off of Scripture. Evangelical pastors typically choose the passage they want to preach on -- this is called "the Individual Choice Method." Catholics, and many Protestant denominations, follow "the Lectionary Method." This means that the readings are pre-set.
The advantages of the Individual Choice Method are obvious -- you have pastors playing to their strengths, the passages that they can recite by heart. They're on "home turf," so to speak, so the quality of the homilies is often very high. I can't really fault this -- after all, "individual choice" is what guides my choice in blog topics. It isn't as if all Catholic bloggers follow a list of Scriptures we have to react to every day. But the Individual Choice Method has some serious drawbacks. Most importantly, it means that you view Scripture through the lens of your pastor, and you view only those Scriptures he finds important, or which he understands well. If he is keen on faith alone, don't expect to hear a lot of sermons on James 2. If he doesn't want to upset the divorced youth minister, don't expect a lot of sermons on Mark 10:1-11. You get the idea. This closes the congregation's eyes to the areas his argument or beliefs might be weak.
In contrast, a good Lectionary opens you up to the whole of Scripture. It's the single best way to get the whole Gospel, instead of just a few pieces assembled together. There are a number of other advantages as well. First, the Old Testament Readings are tied to the Gospel in a special way. So, for example, this Sunday's First Reading is from Ezekiel 37:12-14:
Thus says the Lord GOD:The Gospel is about Jesus raising Lazarus from the dead, and includes the promise of a final Resurrection (John 11:1-45). The parallel is obvious. In doing this, the Lectionary itself teaches the congregation that Jesus fulfills the Old Testament promises. No matter how bad the priest's homily may be, they walk away knowing that God promised a resurrection, and He's a God who delivers.
O my people, I will open your graves
and have you rise from them,
and bring you back to the land of Israel.
Then you shall know that I am the LORD,
when I open your graves and have you rise from them,
O my people!
I will put my spirit in you that you may live,
and I will settle you upon your land;
thus you shall know that I am the LORD.
I have promised, and I will do it, says the LORD.
Second, because almost all Roman Rite Catholic churches use the same Lectionary, it means you can go just about anywhere, duck into a Catholic church, and pick up where you left off last time. It's one more reason that Catholics can feel comfortable wandering into a random parish on vacation, and immediately know that they belong there.
Finally, the Lectionary is set up to teach you the vast majority of Scripture even if you only go to Mass on Sundays and major Feasts like Christmas. It's also yet another reason that it's wrong to miss Mass on Sundays -- the Sunday cycles are set up as a Scripture 101 for people who aren't reading the Bible at home like they should. A person going to the bare minimum of Masses will, over the course of three years of Mass-going, hear all of these Scriptures (bear in mind that those going daily get most of the stuff not here). The list is way too long to post, so just go to the link.