These "invitations" are a bad deal. In general, the dealership does a lot of BS type checks and charges $200 to $450 depending on how rapacious they are and how naive they think you are. There are marketing firms that do these mailings for them in some cases.
If you read the owners manual maintenance section carefully, you will see what needs to be done and when, and that many of the service items are visual checks only. You can do the visual "checks" yourself. The key things are
- oil change at least when the oil change monitor says so, OR no longer than a year, or at least TWICE a year if driving in freezing weather, OR 4500 miles. Use synthetic oil ONLY in thsse hot running engines.
- Transmission fluid in MOST vehicles is good t0 100,000 miles, but in the SSR I would say a Maximum of 25,000 miles because the hot running engine heats up the transmission fluid a LOT (which you see if you have the auxiliary guage package on the 03 and 04)
- Air cleaner needs changing (or cleaning of a K&N or similar) at LEAST every 20,000 miles, sometime sas often as 10,000 miles,depending on ambient environment.
- Most quick change oil places can do all those visual checks the manual talks about as part of their oil change ritual. because they hope they can sell you the service and parts if they find something is needed. THAT is a LOT less expensive than your local Chevy dealer.
- Any brake shop would be delighted to check your brakes pad wear for you, hoping that you will buy new ones from them if needed.
Don't get sucked in by the "invitations" unles you have lots of extra cash you want to give away.