My wife's first (recent) purchase was a SW 637CT. 5-round .38 cal J-frame revolver. The only thing we sort of regret is not waiting for one with the shrouded hammer (the hammer spur of the 637 makes it a little tougher for her to carry discretely) but she really liked the Crimson Trace grips on it so it came home with us. Looked at the concealed hammer version but we like the option to shoot SA if the mood strikes.
Lately, haven't found much .38 ammo at WallyWorld, though it seems to be pretty plentiful at gun shows now (reloads, mostly). We have some factory JHP for her to keep in the gun but she practices with the reloads.
I'm sure a Ruger revolver like the LCR would make a good choice, too; we don't have one (all our Ruger revolvers are new model SAs).
I sort of steered her toward the revolver because of their relative simplicity. Of course, since then, she's come home with a couple 9mm guns; a Kel-Tec PF9, which is nice and small but kicks like a mule, and a compact Springfield XD.
Moral: One is never enough.