It is very important that she gets her sleep! 11:30!! That is crazy! Sleep deprivation in young children has been linked to hyperactivity, short attention spans, lower IQ and difficulty learning new things. Scary stuff!
You really need to get her down earlier- like around 7:30!!
Since she is so old, probably the only thing that will work is the Weisbluth method. Get the book Health Sleep Habits, Happy Child by Marc Weisbluth.
Here is the schedule I follow with my son who is 12 months. He wakes up around 7:30, naps at 10:30 and again at around 2 and goes to bed between 7 and 7:30. Since your daughter is a bit older, she may already have given up the morning nap and that's ok. But if she is tired in the morning, you can still put her down for one. It's most important that you have a regular before bed routine that she will remember and will expect after a while. She will be much easier to get to sleep if she is on a schedule.
Here is what I do before bed:
After dinner, turn the lights down in the house, keep the tv off and keep the house quiet and calm. Bathe her, get her pjs on, brush her teeth. Go into her room and keep only a little lamp on. Read a few stories and then turn off the light. Then give her her favorite stuffed animal, blanket etc and cuddle her for a few minutes in the dark- sing a song, etc. Lay her down in the crib, kiss her good night and tell her you love her and leave. She will probably be upset and will probably cry, but you have to set limits and teach her that it is bedtime. It will probably take a week or so before she understands that this is bedtime. But you have to stick to the new routine or it won't work. The more you go in, pick her up and comfort her, the longer she will stay awake. You have to remember that you are the parent. If you can't get your 17 month old to go to sleep on time, how will you ever get her to obey you as a teenager?