Hi, Gordon, and welcome to the forums. There is no "right" answer to your questions; people do all of the things you mention for a variety of good reasons. You'll have to decide which solution optimizes your requirements -- cost, space, bandwidth, scalability, manageability, redundancy, longevity, etc., etc.
In our own remodel, we're using an all-overhead approach: a mix of pre-terminated Cat 6A (Panduit QuickNet) and fiber for horizontal runs, in-rack switches for management networking, in-rack patch panels for commodity and SAN networking and redundant switching at separate locations. To retain flexibility, I recommend a design that allows racks to be replaced, as neded (so, no internal rack-to-rack or pass-through cabling, no hardwired connections, etc.).
I'm sure others will chime in with opinions. Here are some resources where you can read up on cabling:
- Build the Best Data Center Facility for Your Business, D. Alger, Cisco Press, 1-58705-182-6
- Enterprise Data Center Design and Methodology, R. Snevely, Prentice Hall, 0-13-047393-6 (Sun Blueprints series)
- Telecommunications Infrastructure Standard for Data Centers, TIA/EIA/ANSI Standard 942-2005. (Hardcopy version recommended from IHS/Global)
- Cabling Installation & Maintenance magazine
Ken