I use a parents room when there is one, but since having my DD have no issues in using a disabled toilet if there are no parents rooms.. (mind you, I felt so guilty the 1st time I did it).. Much safer to have bub in your sight at all times..
I think we should stop calling them 'disabled' toilets and start calling them 'accessible toilets' because mums with prams need them just as much as people with disabilities!

I was waiting for a disabled toilet with DD once and the woman who came out WASN'T disabled, she wouldn't look me in the eye LOL.