In a welcome break from the purse and messenger bag paradigms, the O Yikes! slingback diaper bag is cross-strapped backpack, just like the one you bought when you were launching your DJ career back in your Williamsburg days.
Now that you're back working for The Man, there's no need to dredge up painful memories by pulling out your old bag, unused though it may be. Better to eBay it and get the O Yikes!, which comes with a whole host of purpose-built components, like a bottle holder, changing pad, a wipes holder, and a food/etc. bag to match. And if you act now--and pay another $30--you can buy it "Ready-To-Go," stuffed with supplies and a matching O Yikes! Onesie to boot.
That'd make it an extra-thoughtful gift--if you don't have to dump half this stuff at security when you take it to your friend's shower. Thoughtful may be thoughtful enough. [And for old schoolers, they have a messenger bag format, too.]