I usually use multimode fiber, for the short, small jobs I do involving fiber. OM3 I believe. I get a media convertor with matching connectors and we're good to go.

The IT guy is getting involved in my latest fiber project and he has shown me some fiber modules for his switches, and asked which one to use. I asked my fiber supplier, and they aren't committing either way. They say it's up to what they are going to connect. Here's the info:

SFP transceiver 1000Base-SX - LC multi-mode (up to 1640 feet).
SFP transceiver 1000Base-LX - LC single-mode (up to 6.2 miles).

IT guy says the single-mode is only $20 more, so why not get 6.2 miles worth for the extra $20. (I don't think that's the way to spec out fiber smile ).
My fiber supplier says it depends on what they are going to connect. Just LAN computers, IP phones, general stuff.
There will be three runs, the longest single fiber run will be <500 feet. All in new surface conduit inside the plant.

How do you choose?
Thank you.

Jim