Assigning Acuity level to pt

I am working on updating our current method for assigning an acuity # to a pt. I work on a PCU-post surgical/ortho floor. Currently we use a 1-2-3 system with 1 being the most acute and 3 being the least. Currently the individual nurse writes the # next to the pt. before change of shift so the teams can be assigned appropriately. It seems that we use #2 too much and reserve #1 for those that tend to be a difficult pt to deal with and very rarely #3. Some nurses will give their pt. a #2 just because they are pleasant and cooperative even though they need blood,multiple meds and have a lot of pain. We used to have a standard to go by but it has fell to the wayside quite a few years ago before I worked there. We get a lot of total joints,abdominal surgerys,chest tubes,isolation pts.fem-pop bypasses.TURPS etc. Any help is appreciated. Thank you.