Here are summaries of five of the Alhambra expansions with links to detailed video reviews by Tom Vasel. He gives opinions on which ones are the best and which ones are not worth it. I've included some highlights from each video. I recommend watching and deciding for yourself. All quotes are from Tom Vasel.
Expansion 1 "The Vizier's Favor"
Alhambra Expansion 1 Review
On BoardGameGeek rating as of 2012-11-09: 6.09/10
Expansion one is my least favorite of the five expansions … if I was buying the expansions separately I think I would skip … as part of the Big Box, fine
"The Vizier's Favor" allows players to buy a token out of turn once with exact change. May refresh the ability at the cost of all their actions on a future turn.
Ok … would use occasionally, but not one that I would get too attached to
"Currency Exchange" cards are shuffled into deck, can be taken instead of a currency card. Can be used to allow use of currency of one color for a different color as shown on card.
I like this module … best module from the first expansion … a lot of fun … would play with these much of the time
"Bonus Cards" cards that show specific buildings are dealt secretly to each player at beginning of game. During scoring if you have built the building shown on your card you may reveal it to count as an extra building of that type.
By far my least favorite of all the modules for all the expansions … for the most part [it never matters]
"The Workers Huts" new building tiles that are placed in stacks beside board. You may take a hut for free, but are limited to three per player. During scoring is worth as many buildings as the number of adjacent buildings of the same color.
An expansion I use all the time
Expansion 2 "The City Gates"
Alhambra Expansion 2 Review
On BoardGameGeek rating as 2012-11-09: 7.11/10
If you only get one expansion … then expansion two by far is the best one
"The City Gates" cards are shuffled into the deck, may be taken when revealed. Allows you to place a gate token over walls to ignore them when building.
If you find yourself hemmed in and you need to add more tiles, this is an excellent expansion in that regard … really cool pieces … a module that I really like
"The Diamonds" new currency shuffled into the deck, essentially wild cards, can be used as any currency, but cannot be combined with regular currency.
I really enjoy the extra currency. This is another module that I really enjoy and it's one that I will almost always stick in the deck.
"The Characters" several characters are shuffled into the deck, when one is revealed there is an auction for character. The bids must be single color currency. Each character grants owner special abilities.
Something I like using, I won't use it all the time … it adds special powers to the game
"The Camps" camp tiles are added to the bag. Must be placed with wall adjacent to a wall of your alhambra. During scoring you get points for each tile in the row or column indicated by the camp.
My favorite module, I almost always play with this module because it adds a lot of enjoyment even though it's a simple change …
Expansion 3 "The Thief's Turn"
Alhambra Expansion 3 Review
On BoardGameGeek rating as of 2012-11-09: 7.03/10
My second favorite expansion … the main reason is the coin module
"The City Walls" cards are shuffled into the deck, may be taken when revealed. If taken you will place walls onto a tile already on the board as indicated by the card.
There's an module in expansion four … this is a good combination with that … I use City Walls sometimes … it just feels a little fiddly
"The Thieves" cards that show a a specific currency are dealt randomly to each player at the beginning of the game. You may play the card out of turn to take a currency of the indicated color.
It's okay … but it has a limited amount of uses.
"The Change" coins in each currency are placed into a bag. When you buy a tile, if you overpay for every two currency you overpay you may draw one coin from the bag. Coins may be used as one currency of the indicated type.
This is super fun and makes it into almost every game I play … neat idea
"The Street Trader" a market tile allows you to place meeples on tiles you build under certain conditions. During scoring sets of different colored meeples are worth points.
An interesting idea but changes Alhambra to a huge degree … it feels very convoluted … it takes away from everything else
Expansion 4 "The Treasure Chamber"
Alhambra Expansion 4 Review
On BoardGameGeek rating as of 2012-11-08: 7.10/10
I like the fourth expansion almost as much as I like the third … some decent ideas in this expansion
"The Treasure Chamber" different colored treasure chests are placed randomly in lots of four on a treasure chamber board. You may use your turn to pay 8 currency of any color to buy a lot of treasure chests and place them on buildings in your alhambra of matching colors, extras are discarded. During scoring the player with the most treasure chests earns points.
I like the treasure chests, it adds a lot to the game without making it too complicated
"The Master Builders" cards are given to the players and added to the deck. They can be used as three currency of the indicated color, or can be used to take an extra realignment action.
I like having all the extra threes in the deck … it's not the greatest of the modules but it's a good one
"The Invaders" In each scoring round a card is revealed to show which direction invaders will attack. Tiles that do not have walls in the direction of the attack lose points. Scout cards help to learn the direction of the impending attack.
It's a neat idea, and yet one of my least favorite of the modules … everyone gets so worried about the attacks and the points they take off aren't really that big of a deal
"The Bazaars" bazaar tiles indicating three colors and a currency are added to the bag. When they are revealed they may be bought with exact change of the currency indicated. At the end of the game the bazaar is worth points based on adjacent buildings matching the indicated colors.
I really enjoy it because it allows you to build your alhambra bigger … they encourage diversity … I really do enjoy playing with [this one]
Expansion 5 "Power of the Sultan"
Alhambra Expansion 5 Review
On BoardGameGeek rating as of 2012-11-09: 7.04/10
Should have stopped while they were ahead, I almost want to call this the convoluted expansion … I'm not a huge fan of expansion five … there's some neat things in it that I can use … it seems like they're running out of ideas
"The New Score Cards" new score card tiles allow for building colors to be valued randomly for each scoring round.
This adds some variety … I like this, it makes you look ahead … a good expansion, one I use quite often
"The Power of the Sultan" a sultan card and die allow for a tile of a specific color to be taken for free.
A bit of forward planning … it feels kind of odd … it's not one that I want to use very often … the amount of work put into it doesn't seem to be worth the payoff
"The Caravanserai" a card can be purchased that can be used for different, increasingly valuable currencies each turn.
Like a constantly recharging currency … not as great as you might think because while it's reusable it does take a while to [gain value] … despite all that I like it … not one that I would use all the time
"The Art of the Moors" playing matching tiles can lead to points at the end of the game through some complicated mechanics. Also has some tile reference cards that are useful regardless of expansions in use.
In essence, a very convoluted … way to score the tiles by numbers in addition to scoring them by colors … I don't really know what to think about that … too complicated