Looking back at the various shirts I've received and enjoyed, It seems that there is a pecking order with regards to prestige of the event and the type of shirt we receive. Most large public and local regattas have standard t-shirts and most are quite cool. However, as the prestige level goes up, we first graduate to long sleeve t-shirts for national and big event (Performance Race Week, Tybee 500). Then we step up to shirts with collars for events like our Alter Cup Qualifier (thanks Nigel!) and to a long sleeve collared shirt for the Alter Cup itself. Obviously, there are some exceptions.
I have a ton of t-shirts such that we're searching for additional storage for them all. I like the idea of a polo shirt with a simple but elegant logo.