Cook her dinner, don't try and pump too much wine into her though, thats cheezy.
When its nice out:
Take her on a walk around the Iowa State Center where all the walkways are lit up (well should be, but they need to replace a lot of light bulbs). Bring a blanket, stare at the stars.
Hopefully no foxes are killing bunnies in those bushes, because I did with a date, and the screech kinda ruined the mood.
Take her out for desert after that, sometimes a simple cone from DQ is all it takes!
