For me the variety is one of the main attractions of punting, i've seen a few girls more than once, but dont be fooled into thinking your'e special or getting a better service than anybody else, only return if you really enjoy it and they give value for money, if not move on, don't feel obligated.
i'm a sucker for ebony babes, and also girls from different countries/cultures, if your'e going to pay it may as well be for someone who's out of your league anyway.

But location can be important, its nice to see a regular in a nice apartment with secure access and easy parking, can be a pain finding new WG's!