A separate bath and separate shower are the best value for everyday use and for resale. The shower/bath combination is historically a hangover from Britain, where most people used to have a bath, instead of a shower. Most Australians prefer a shower to a bath, and a shower over a bath is always a compromise.
Having access to a bath is important for a family with young kids, but you don't need a huge, long bath for children, so a 1500mm long bath is ample for kids, but a little cosy for a tall adult.
As far as resale goes nobody ever did not buy a house as it had a separate shower to the bath, but a shower/bath combination can be enough to turn a buyer off.
Best of luck,
of Dr Retro House Calls