Having a "stack" of testimonial letters could be impressive, but will they get read? They may also all say basically the same thing; you are a "great", "super", "wonderful", "excellent" salesperson.
The residential listing appointment often goes 45 minutes to an hour or more and the owner may have time to read several of these letters. But on the commercial side our appointment may only be 15 minutes! There is great value in testimonials but they will need to be consolidated for our presentations. One page with perhaps 8-10 quotes from satisfied customers can be sufficiently impressive.
I have always found it uncomfortable to be sitting at a closing table and to ask my customer, would you write me a letter telling me how "great" I am! Of course this could be worded more subtly, but the result is a stack of similar sounding letters. I have even heard of some agents writing the testimonial letter for their clients and just asking them to sign it!
I get my testimonials anytime and anyplace. I may be showing a building or on the phone with a client and they say something nice about me. "May I quote you on that?" is my reply, and nobody ever says no. This gives you the ability to get many different comments that can tell a story.
"We should have listed with you sooner; you sold our building in record time."
"What a great job leasing our store. We never expected to get a National Tenant."
The key with effective testimonials is to use them to demonstrate the benefits of working with you. From the above, a retail client realizes you have contacts with National Companies.
"Thanks for the tip on 1031 exchanges, you saved me a fortune."
"Saved me a fortune" will get anyone's attention. If the seller never heard of a 1031 exchange, you get to educate them, if they have heard of it they know you are a professional based on the quote.
Testimonials are generally used in listing presentations; however they also may be used when seeking buyer or tenant representations. In your page of quotes include some for this group too.
"We have been looking for space for months; I can't believe you found us the right spot in weeks."
"You located a great building for us and it was not even on the market yet!"
One of the benefits of using a real estate agent is our existing relationships. The ability to call a building owner we worked with before and determining if they will have space available soon or if they, or someone they know, may be considering selling a building. This last comment implies that ability.
Listen to your clients and customers and remember you are always looking for testimonials. Your goal is eight or ten different quotes that tell a story. Update them regularly.

Edward Smith, Jr., CREI, ITI, CIC, GREEN, RECS, is the eastern regional director of Coldwell Banker Commercial NRT, Syosset, N.Y.