The S&W M&P Shield is a great choice for an all-around carry with a safety for someone with smaller hands. Single-stack 9's in general are great (thin!) and there are MANY choices now. Biggest problem with a Shield may be in FINDING one... They don't stay on the shelf more than 5 minutes.
Here's a nice video which nicely shows the thinness difference between single-stack and double-stack: