Recommended Postgres settings to speed up indexing on a 100GB database?
If I were setting up a new server, I wouldn't use anything below 9.3.6.  There have been many improvements since 9.1.  

And if you use 9.4.1, there is some code to let it use larger amounts of RAM for index creation than it previously could.

Neither of the parameters you listed are particularly important for creating indexes.  The most critical for that purpose would be maintenance_work_mem.    On a 32GB server, if I'm only building one index at a time and keeping a close eye on things, I'd set it to 16GB for the local session that is building the large index.

Also, the C collation is much faster than the other collations, if you have a choice.

Is the bottleneck CPU or IO?