There were times when the 64bit version gave problems, but now it is recommended if your computer can run it, because with 32bit version you might end up having memory issues. Not sure if this is still valid nowadays, though.
People having crashes when playing with Steam is not unheard of, but I don’t remember the workaround for it.
Maybe searching in the Crash report category could give you more hints.
We had a topic for crashes because there was a time when lots of people started having crashes due to third party software:
http://discourse.stonehearth.net/t/crashing-on-start-read-this-updated-november-29/13297
But in your case only crashes when you run it from Steam, so I don’t know 