From a long term business and personal client:

This letter is to thank you for your excellent representation on the wide variety of matters that we have presented to you over the past several months.

Your timely, capable and honest dealing with us has meant a great deal as our business grows and develops. We look to you as a source of trusted advice, and we have been very impressed with the quality of your legal services.

We feel fortunate to have made your acquaintance, and while we feel we are probably one of your more demanding clients, we would like to take this moment to say “thank you.” We look forward to a long and mutually rewarding professional association.