As for as The Gap goes, this is the best location I've been to by far! They have all their brands - Baby through Adult, Gap Body, and even a good sized Maternity section!
I have not had success finding affordable maternity clothes, but hit the jackpot here. Sure, the jeans are a little expensive at $70 but there are a lot of great staples and some more dressy items. They even had a couple maternity workout tops! On the downside, not a single staff member asked if I needed help the entire 45 minutes I was browsing and trying stuff on and browsing and trying more stuff on. I didn't mind though, sometimes it's nice to be left alone.
Get on their email list for coupons and check this Gap out!