Puerto Rico - Custom gameplay tweaks to introduce player interactions
Puerto Rico is mostly an open information game. The plantation tiles are randomized and hidden information, and VP points are hidden, although a player with good memory could count when each player earns victory points. 

There is player interaction in Puerto Rico, but it isn't like Settlers of Catan wheeling and dealing, which allows multiple players who are losing to trade resources among themselves to help each other catch up to the leader. The other two games are very similar to Puerto Rico in their player interaction, in Agricola you can deny your opponents a particular role when you choose it, and in Le Harve you can get your goods to the ship first blocking the boat. (It is confusing that you mentioned them)

I almost never see a player waiting to use newly acquired buildings, any longer than the one round that would be necessary to choose the Mayor action to fill the building/plantation. Puerto Rico is designed as a resource management game. Nearly every turn, it feels like their are two things you need to do, but you can only choose one.

Can you modify the rules to allow trading coins for building use, sure but there will be added complications.


Do buildings "open for business" still require a colonist from your opponents to use?
Do your or other colonists "block" a open building for use by other players? (i.e. are the number of circles relevant on buildings)
How will players indicate they are using your building if colonists are required, how do you keep track of which colonist is which players?
If using a building doesn't require a colonist, when can a player decide when to use it? (i.e. Can I use a Factory right before/after crafting, a Storehouse/Harbor during shipping, etc?


If you think about adding this feature, realize what you are doing. You are allowing other players to trade coins to another player for Victory Points. How many players are going to leave their Guild House, City Hall, or other large building "open for business?" Why would I make my Harbor available to anyone else, when the point of getting it was so that when we ship, I get +1-2 extra VP? I am pretty sure you will find this rule rather pointless.