It depends on the type of building, but most of the installations I see are mainly fibre within the building.
Our network here is fairly typical; from the main core switch we have copper to the servers in the same room, and 16 core multimode fibre, mainly OM-3 laser optimised now, out to the various comms rooms around the building; there is one of these at each end of each floor, blus a couple of additional ones, and a few more are being added. From the edge switches in these rooms it's copper out to the desktops, and to a few attional servers, telephone system etc. We've also got fibre through the underground car park to another building; this is OM-1 fibre, and just within distance for it. From that building we have copper out to some temporary 'hut' type buildings in what used to be its car park.
To another building just across a road from the main one where we rent some office space we have two 100 Mb laser links on the roof. Until recently we had a wireless bridge feeding one PC in a 'shed' on a roof. We also have a 1Gb fibre link to another site, about 2-3 km away which we are using for about 3 years during major refurbishment of our main building, but this link is not ours; it;s a service which we buy from BT. Obviously this link is single mode fibre, but it terminates on a NTE box at each end, into which we plug our own multi mode fibre. BT monitor this line via an ISDN connection at one end. A similar fibre link, but at 100 Mb provides our Internet connection; in this case the user's connection on the NTE box is copper. Within the building on the end of the 1 Gb link is all copper, because we are using the existing, terrible, cabling that was in that building; for the short time involved it wasn't worth having the whole building re- cabled, but many of the lines are over-length for copper, most of the socket modules on the ends are poor quality, and there is only one strand of Cat. 5 run to most of the cabinet positions around the building. I we were going to use this building for longer it would have been re-cabled with fibre.