Gymboree for us. I bought DD a few really cute sleepers at 2.5 months so I went up to the 3-6 month size and they're tight! She's only in the 45% for height and weight too. I'm bummed because they were kind of expensive. I should add that 0-3 months in everything else is a little big on her still but she's out of newborn clothing.

What brands have let you down as far as sizing?