Whats the safest cactus plant that still looks like it has sharp spines to have around the house with pets and kids?

Any kid or animal that touches a spiny cactus once and comes back for a second try is retarded and should not be in your house.

We've had cacti in the house since we were married and no child or animals were harmed.

I don't know about a spineless cactus, but I was just in Arizona, and the cacti in public areas all had their spines sheared off. You could do that. 

Perhaps the genus Stapelia. They are succulent but look like cacti and can live with little water. They do not have thorns.