Oh migod...I love this bag. I took too long thinking about buying this bag, it sold out at Saks (haven't seen it anywhere else). I see your dilemma, they're both beautiful colors for this bag......blue seems more on the trendy side and black is classic. I think the blue is more edgy and it's a unique handbag color. I've seen the blue on so many celebrities, that I didn't even know that black was optional. Go for the blue!
angel, I'm glad you like it (that's my pic of the navy ramona and gerard darel charlotte bag), but the navy is really close to black. Almost indistinguishable. So if that bothers you at all (that it's almost, but not quite a match), then I would go for the black. Personally, I had hoped the color would be more like the Chloe paddy bleu nuit. In some pics of Lilo, it looks that way. But it is definitely very, very dark.