really like hurley for casual clothing like tshirts and walk shorts, oneill has some nice board shorts and collared shirts, and then things like oakley, billabong, quiksilver all have nice casual wear too if you're kind of plain like i am.
i'd highly recommend shopping online on the hurley website though if you're looking for some good tshirts (especially their heathers) which are thin, light, and have a great fit (not too tight around the neck, sleeves are mid bicep with a good fit).
the majority of my solid colored summer tshirts are hurley and i love them. their walk shorts are pretty sick too. great fit.