C.R.
Does your child have frequent ear infections or respitory (sp?) symptoms (i.e. snoring, congestion, etc.)? In my son's second year of life, he began to wake up several times at night and getting him back to sleep was a bear! He also snored all the time! After a bout with two severe ear infections we took him to an ENT, he ended up having tubes put in, as well as adenoids and tonsils removed. Once this was done, it was like night and day! He slept soundly all night long and no longer snoared.
Another possibility could be (as you suggested) she wants the attention. Maybe you can try giving her more of your time before bed. Read her an extra book, play a game, and assure her that she is loved and important! I have four children as well, finding equal time for all of them if very difficult. So, GOOD LUCK!