Unfortunately most of the ones I'm familiar with are geared towards restaurants, not retail. So I don't have any specific recommendations off hand but I'll ask around to some people I know in retail. I know my favorite homebrew shop just started moving to a computerized POS system and I would imagine that would translate to your business so I'll pick their brains a bit on what they went with.
Shopping for a POS system can be a pain in the ass, you need to be aware of any hidden costs (for example, they might have all the marketing tools you list but will charge an extra fee for the "marketing package") and the salespeople often seem like they were rejected from used-car sales school. Is there any sort of fish/pet store trade shows or something you can attend to get some hands on experience with them?
Also do you want to purchase hardware or get a system you can load onto any computer? What about things like receipt printers and cash drawers, have those already or looking to buy? Other features you might consider is remote access, possible online ordering integration, employee scheduling and time punch management, etc. Finally what kind of budget are you working with? Willing to pay a monthly service fee?