I've been playing a fair amount of Carcassonne with the basic tiles and the original River expansion. What other expansion packs will add a bit of variety to the game but without changing the character too much? I've heard Inns and Cathedrals is pretty good but don't know about any of the others. I'm especially interested in any that work well with 2 players.
The chance with the builder to draw two tiles can make a huge impact on the game so it adds a dimension all on it's own. I however personally prefer not playing with the Traders part (the cloth, wine and grain tokens) just the builder and the tiles.
Bridges makes for some interesting escapes and castles is a new fun thing to do with those small cities. As above I preferably skip parts of this expansion which is Bazaars (tile auction).
Pretty straight forward expansion that adds Inns (a road with an inn somewhere along it's path is worth 2 points when complete (0 if left unfinished) per tile. Cathedrals are in cities and makes the city tiles worth 3 points if completed (0 if not completed) per tile. Great ways to remove others points if drawn late in the game. Also the big meeple/guy is in here iirc.
This one, unlike first expansion can split and create two streams.
Finally I just recently started added Carcassonne: The Cult to my bag. Works just like cloisters but if you put it next to a cloister only the one scoring first gets any points. So far it's fun but it's only some 5 tiles or so.
The only expansion I have besides the original River is Inns & Cathedrals, but I'd say it's a necessity. In addition to ramping up the stakes and adding some interesting tiles, it adds the big meeple, with adds a lot of fun to hostile takeovers.
My wife and I regularly play with Inns & Cathedrals and Traders & Builders. We're mostly interested in having more tiles for a longer game, but the extra rules do add some variety. We sometimes ignore the expansion rules and just use the tiles, especially if we're feeling lazy or playing with less experienced players.
Inns & Cathedrals
We use this one primarily for the extra tiles and the big Meeple. A lakeside inn has little effect in 2p unless one player finds a way to hog them and complete those roads. We score more total points, but they're usually split evenly. A cathedral becomes a late game screw-you tile in 2p (our games get kinda cutthroat). Play it on a big city to make it unfinishable and thus worth 0 points.
Traders & Builders
The builder meeple is critical in 2p. You have to make good use of him or else the other player is going to run away with the extra turns. As for trade goods, I usually see them as an equalizer against bad tile draws. You can finish your opponent's city in exchange for a chance at +10 or even +20 points at endgame. That's not always a good play in 3+ player games, but it can help a lot in 2p. Assuming one of every trade good ends up in a completed city, somebody is going to at least get a 10 point advantage. That's a big deal in 2p games.
Carcassonne is one of the most expanded board games around. Last time I checked there were 8 full expansions, and 10 mini-expansions. The River is an example of a mini-expansion, and Inns and Cathedrals an example of a full expansion.
I have only played a few of these expansions, so cannot offer my view of them all, but when choosing an expansion, I went for Traders and Builders. It adds a little more dynamism to the game by encouraging cities to be completed sooner, and makes farming more beneficial. This generally suits my preferred style of game, which is why we bought it.
The other expansion bring different dynamics to the game. I would encourage you to check out the link below, and see which one sounds good to you, and hopefully others who have used other expansions can tell you their findings as well.
A full list can be found here.
I would highly recommend the Inns and Cathedrals for a reason no one has listed that I've seen. If you play with Inns and Cathedrals, it allows you to play with 6 players. I often like to invite a couple of couples over to play board games with us, and 5 players is a rather odd number to be playing with...
I would take the recommendations of getting at least the first two expansions (Inns and Cathedrals and Traders & Builders), any of the other ones are just icing on the cake;-)
Inns & Cathedrals is essential. It's a great expansion containing meeples for a 6th player, the big meeple, and some nice extra tiles. Traders and builders is also good. It contains the builder and trade goods. Both these expansions are really good and are sensible to get as your first expansions. Next could be Abbey & Mayor, which contains the mayor, the barn, the abbey and the cart.
Well, when You have couple of expansions (four or more) they could destabilize the entire game. Since only one exp add features to roads (and road sucks with official exp's), You could print some exp from carcassonne central. Roads to Victory, Seasons, or By the Order od King, they adds very much to game.
I add something from my own experience:
Abbey and Mayor It adds a lot of variety in my opinion. It introduces a "super cloister", a "super knight" and the "wagon" that is very interesting. Needs experienced player in my opinion
The Ferries Some road fun finally.
I agree on the above answer with River ( combine 1 and 2) and Bridges, inn and cathedrals, builders and Traders, castles are a must have.
With all above you have already a lot of tiles, fun rules, and no nonsenses.
Expansion that i have and i do not recommend: -Princess and dragon -Tower Basically those are based on meeple removal that is a feature id do not like. Also keeping track of the fairy is so annoying. Interesting point from princess and dragon is that it adds 30 tiles to game, so maybe it can be bought for this. Other mini expansion ( 1 - 2 and 4 and 6 ) looks like useless. Bazars