Try taking a look at the Sabre suite of systems, individually they may seem expensive but taking the whole suite will save time and money integrating with your current systems. The Sabre AirCrews system boasts good optimisation software for building duties and making the assignment.
AIMS is always prefered by the users as it is very user friendly so makes it a lot easier to get the buyin of all the staff.
My advise is to speak to the suppliers and ask them to arrange a field visit to one of their clients.