I'm having a really tough time with this. I have my parent's house in Cortana places as "Parent's House". I tried saying how long will it take to get me to my parents house and Cortana just gave me directions to my house. I tried changing the nickname to "my parents house", "dave and Ellen's" house and even just "apple" and saying "driving directions to apple". In all cases, Cortana just tells me how to drive home.
Furthermore, when I try to use Cortana to search the web for "why does cortana always default to driving directions home", Cortana immediately opens up driving directions with Here+ to drive me home (which is where I already am)
Kinda frustrating... Anyone else experiencing this? I just got 8.1 on Verizon. Not too impressed with Cortana.