a) Find/adapt a 24/48 thread inside-plant cable (either multimode, or condition single mode) and connectorize the ends. Adv: Clean, Single, high density cable runs, Dis: Not sure if such a beast exists in multimode, and the whole cable has to be replaced/made redundant if one fiber dies and you need a critical restore, may need a break out shelf.
We use multicore fibre cables in our datacentre and nodes. In Europe we can obtain these to order on specific size. If we need to bring these back to a central area we use an ODF and and then patch accordingly with fibre boxes in cabinets. The multicores are in a rugged PVC type plastic sheath [same type of plastic/pvc that is used for gas piping in the streets here in Europe]. You have to do some serious hacking to damage this type of cable, and if you've ever been to Telehouse in London you'll know how the type of situation that I mean. This is the company we use in the UK to do a lot of this work http://www.mainframecomms.co.uk/products_cables.html I can't recommend them highly enough. You may also want to look at passive optical stuff that you can use to cheaply use to do cdwm. Regards, Neil.