All good suggestions. For ladies, Abingdon makes good aviator style watches that are female-sized and not too expensive. I got one for Christmas and it looks nice without me worrying too much about bashing it on something in the cockpit.
Though inexpensive, a nice leather patch for her flight jacket is an option too. Wings and things (in Pensacola) and Tipsy Gypsy are both popular options. Of note, despite uniform regs don't get the "proper" "A.B. Winger 1stLt USMC" and instead do "First Last US Marine Corps." This will prevent her from having to switch out patches (damaging the leather) every time she promotes.
When I winged, I got from my parents a print from squadron posters and my patches from flight school squadrons mounted and framed.
Where is she winging out of and what platform? There are some more practical options that will help her out depending on where she's going (tablets, flight bags, etc.).
Whiting Field/rotary - UH1 or CH53 (not Cobra/Viper if she has the choice)