Pros
Really enjoyed my seven years at Zachry. I should caveat that I was hired a couple of years after Zachry acquired the engineering firm in Amarillo, and I was hired into that office environment with a small procurement team. It was a tight group, and working alongside engineers on new EPC projects was complex and satisfying. I learned a lot about the engineering process from concept (bid) to execution, and all of the related commercial activities.
Cons
Management was always focused on centralizing (to the corp. office in San Antonio) everything that it could. This led to regular rumor-milling among satellite office members about when the hammer would fall on our location (and eventually it did, with the majority of the Amarillo office being laid off or sent to other locations). Senior management also tended to be myopic and territorial, especially in Procurement. And like many corporations, the least competent but best connected / like individuals tended to be promoted (or have positions created for them!). That eventually grated on me.