If its not cold where u live take her on a hot air balloon ride, small plane ride or skydiving. I took my girlfriend with me skydiving a few different weekends and the pilot let her fly 2 different loads all the way up. She really loved it and most smaller plane pilots let passengers take the controls after take off. She took a load of 17 jumpers and a load of 13 I think it was from 500 feet or so up to 14,000.

Anyway it may not be very realistic since its expensive but she was smiling from ear to ear for a very long time. About 500 bucks for a 2 person hot air balloon ride for 1-1.5 hours somewhere. Observer rides at dropzones cost about 20 bucks or so and 1st jumps around 200 a person and 80 for video if you want it.