When choosing your suite consider:-

How big is your bathroom, think about the space available for the positioning of your suite and don't forget room for opening the door.
Will the available space accommodate the bath of your choice, considering plastering and tiling, these few millimetres can make the difference between the bathe of your choice and having to choose again.
Do you have a water tank that can be relocated giving greater scope?
Do you wish to replace your bath with a shower cubicle?

Are the wall structures of your bathroom suitable to support and  conceal fixtures, fitting and plumbing?