Games can generally be divided into two categories: too simple to be interesting and too intimidating to convince others to play. Where an individual game lands depends on your gaming group, but there are almost always games someone would like to try that are gathering dust because the time never seems right to tackle them. (I'm looking at you, Advanced Squad Leader and Advanced Civilization.) So the most played games tend to be lighter and (for those of us who prefer deep games) a little boring.
Carcassonne is one of the magical games that slips between those extremes. Neither of the two gameplay mechanics are particularly difficult. Most everyone enjoys placing tiles, which presents a simple puzzle not dissimilar from laying dominoes. Though Carcassonne tiles can't be set up as physics puzzles, the map at the end of the game pleases the eye. I'm always tempted to take a picture of my medieval countryside to post on social media.
The other mechanic is resource allocation. This takes a bit more thought for newer (and younger) players. But once you've seen how having a meeple in reserve to score a quick city or road, it becomes easier to resist overspending. There's always the risk you won't have enough to invest in a cloister draw, which also teaches saving. After learning these lessons, Carcassonne becomes easy to play.
Carcassonne comes into it's own as an exercise of delayed gratification. When teaching the game, the rules suggest not using farmers. In fact the current edition pushes farms into the "supplementary rules". It makes sense because farms are easily the trickiest part of the game to teach. (They also have undergone revision over the years.) I might play one game without farms for the sake of easing people in, but I find the game is a lot less interesting that way. Farms add reward for taking a risk.
Farms highlight an obscured territory control mechanic. A great deal of strategy arises from the mechanic of connecting already occupied scoring features. So a player can connect their road, city or farm with someone else's to share the score or, if they manage to outnumber their opponent, take it over. Connecting roads and cities can be modestly profitable, but gaining or losing a farm can swing the game dramatically.
I say territory control is "obscured" because players aren't necessarily aware of how control can be obtained by design. It starts with a seemingly innocent farmer and ends with a "lucky" tile placement joining two farms into one. But good players can grab farms almost at will from unsuspecting opponents. All it takes is knowledge of the outstanding tiles and finding a likely entry point. Cities and roads are also vulnerable, but less lucrative.
As an incredibly accessible game, Carcassonne can almost always get interest from players. But there's depth from the simple mechanics that make it enjoyable for experienced players too.
One trick I've learned with younger players is to allow farms, but also declare a winner before scoring them. That gives people who are comfortable risking farmers a handicap of fewer meeples for roads, cities and cloisters. Non-farmers can enjoy seeing their lead in the scoring track most of the game. Then add in the scores for farms to get the overall winner. That way the more experienced players aren't just dominating and less experienced players have something to aim for.
We also make good use of Carcassonne's lack of secrets. Once you draw a tile, everyone can see where it might be placed and offer advice. In a friendly game, that advice will be genuine. In a competitive game, it might be misleading. You don't want to slow the game down, but this keeps everyone engaged during other people's turns. Even if you don't give advice, watching other people play will be interesting if you need a particular tile or location for your own benefit.
Counting tiles is another mechanic people might not be aware of. If you keep track of what's left to uncover, you will have a better idea of strategies to pursue or avoid. It's also provides a subtle way of blocking someone else's progress. If you know a certain tile configuration has been used up, you can play tiles in a such a way as to block features from being completed.
Our edition came with the river expansion. It simply replaces the starting tile with a series of river tiles. The river is played like regular tiles except they must form a continuous body of water. It doesn't change the game too much, but it creates a more pleasing final board. The river tends to break up farms, which can be good if you don't care for giant swings in advantage. We like to add it when we play, but it's not a major change.
We haven't invested much in expansions. I've played the ones available in the digital adaptation and they add a twist or two. I can imagine wanting a little more variety in the future. So far we don't feel a need to add the expansions we currently own, however.
It's a rare game that can serve as an entry point into the hobby, but also remains competitive for experienced players. Even rarer are games that are rewarding for both extremes in the same play session.