We have a 4 bed 1930s semi that has a cloakroom downstairs & a separate loo & small bathroom upstairs (not next to each other so can't knock through).
We're just about to have the bathroom re-done & deciding whether its worth squeezing another loo in there. At the moment it's just me, DH & baby DD but there's always the possibility of another DC at a later date! The extra loo would probably be to the detriment of some storage & a towel rail.
How useful would a third loo be in future years with DCs? 