Depends on the parameters of the project (the type of project - New, Remodel, etc.).
My answers are bent towards Commercial / Industrial, which may be of no assistance to those in the Forum whom deal with Residential.
* Project - New Work / New Construction (unimproved lot):
Preliminary survey of site; looking for locations of Temp Power / Voice line, and best placement of Materials for Storage, overall ground conditions and related stuff.
Not very much needed to field verify on a completely new project.
* Project - Tenant Improvements, Additions and Remodels:
Prelim. survey of existing conditions regarding demolition and continuity of other Tenant spaces' Power + Comm., existing Electrical Equipment information (maker, ratings, distances, available space, location, etc.), amount of sawcutting involved, what needs to be matched to fit / look original, Asbestos abatement, existing systems and/or equipment to remain as-is, type of Building and Tenants, where to store Materials, how to keep Temp Power and Phone active + safe, are other Contractors "Work-with'able".
* Project - Service Upgrades:
The biggest challenge I face is a smooth and rapid "Change-Over" from the existing power system to the new one.
A typical example: upgrade of an 800 Amp 480Y/277V 3Ø 4 Wire Service, to a new 2,000 Amp 480Y/277V Service.
New Gear at a new location. New Service Feeders to PMT Vault. PoCo increases Transformer size (new Xfmr) and maybe the Primary Feeders.
Working together with everyone involved results in having a Meter set on the New Gear at the time of Transformer upgrade. Cutting everything over to the New Service takes place during this small time window.
The only preliminary site survey data which is helpful on these (for me) is to collect as many facts about what is "crucial" (i.e. Alarm systems, File Servers, Fax Servers, critical equipment, etc.) - and form a great game plan with the crew.
Is this of any help???