However, in every other way the customer may be delighted with the overall service they receive. If you're going to measure customer satisfaction, take a benchmark survey as a starting point, then compare results and improvements at regular (annual) intervals. An excellent measure of real customer satisfaction is referrals. If your customers are happy to independently refer new clients to you, then you could consider that they are happy with your service, and satisfied customers.
Value of Client Business If you are able to offer your customers new products and services, or ongoing offerings, and you are communicating that to them effectively, and making offers at the right price and time, and making the benefits clear, etc, email list the value of each of your key customers should increase. Tracking value is a good indicator of how your client's spending patterns are changing over time. Ideally, you could track them from when they first became a customer (depending on how long you've been running your business and how many major customers you have).
If they continue to spend more with you each year, then this is a good broad indicator that your marketing is paying off. You're doing the right things. If the customer value is declining or stagnant, you need to reassess your specific marketing activities with these particular customers or group of customers.