My
If it's a *Just cuz I appreciate you* I'd go for the full day spa.
Massage - Manicure - Pedicure - Facial (not the ones you dirty minded pigs are thinking of) makeup & the works. Then take her out to a romantic supper.
If you want perfume - I'd say Dolce Gabbana - the whole kit, creams - moisturizer - soap and all.
Purse - You should know which style she wears the most - then find a designer that has something similar. Personally I think - Gucci & Fendi are quite nice.
The best gift? Your honesty, understanding, and faithfulness would probably be most valued - or get a card & tell her what you feel for her and what she means to you.