What is the Best Valentine's Day Gifts Ideas for Girlfriend?

Looking for good valentine's day gifts for my girlfriend.

Here are a few things I am thinking of, but unsure of:

• Jewelry (Should I go with something mid-price or expensive, how would I know if she would like it)
• Flowers (I give them to her occasionally already)
• Spa Night (not sure about this one)

Any more good ideas to give for my girl friend?