Also a reason why you may want to or be asked to pay for the materials directly from the supplier, and just pay them for the labor.  

I don't know about a warehouse supplier, but I used Trafficmaster Lake shore Pecan laminate wood planks from the home depot in my rental.

I am reaching out to investors in the Fayetteville and surrounding areas as I am  looking for a local cabinet supplier who is accustomed to working with investors.

For example we ask for trade references that they use like suppliers of materials, and we call to verify they pay their bills on time.

Systematically blaming the contractant is lack of leadership, and as a business we should not let room to our suppliers/contractors to take advantage. 

Wondering if anyone can recommend door & window suppliers in the Seattle area?

Visit your local ABC Roofing Supply and show them your photosAsk them for the local COMMERCIAL sales reps for the TPO and PVC suppliers ... you want to have them all come to your building and discuss with you their products, warranties, and their "CERTIFIED" roofers; the certified roofers can sell warranties - even if you don't BUY the extra warranty, it's good to know which companies are certified (which required training). 

It doesn't take a genius to watch how contractors, suppliers, etc. treat the manager/principal.

We used to order pallets from a direct supplier before Covid interrupted their supply chain.4) We have separate LLC's under our investment corporation for properties that we OWN.

Maybe start out by signing up for mailing lists for the supplier stores you'll frequent, including the manufacturers' sites of materials you like.