We have 2 cats and a dog...
We have 2 litter boxes in the the only part of our house that the dog and babies can't get to. The Dog, Zoe, eats the poop out of the litter box if they are available to her...

, I know.
Anyway.. one is in the hall closet and one is about 3 feet away from the other and they are both blocked off by a baby gate. We call it the kitty latrine. Let me just tell you that before the spraying he and out other cat shared a litter box since they both moved in with us. Never once had any issues with outside urinating until the kids were born. He didn't seem to care when we got the dog either. He goes in the litter box all the time, so I know he is using it. We clean them daily and really clean them weekly.
He seems to be set off when outsiders come over. We had some travertine installed in our kitchen and when they were done.. what does the cat do? He sprays it. The maid comes over to clean.. he sprays my bathtub. We have a birthday party for Ava.. he sprays the guest bathroom. I know that he sprays around the front door too, and that may be from another cat outside.. I haven't seen one, but this is my guess. I try to keep the blinds closed so he can't see out there.. but he has also sprayed the blinds in the dining room and kitchen.. I am going crazy here. I finally have (had) a nice house with my family and he is ruining it.. and my purse collection..
Sorry for the rant.. I am just frustrated over the whole situation.