What can I do to get my cat to stop peeing everywhere?

He's been doing it for since he was about a year. He has peed on people, by doors, on sofas, in every bed he's gotten, in the shower, in the sink, on my PC monitor, you name it and it has been peed on. He wants to be an outside cat (he got out once when young), but my living situation (apartment complex) and my personal preferences are against that. I have taken him out on a leash, but I think that just makes his desire stronger. He is also pretty competitive with his brother, picking on him when he can't go out and refusing to play or interact when he's near. I have tried Nature's Miracle to prevent the smell drawing him back, I've tried Sentry Cat Repellent, I've sprayed him with water, I've tried Feliway pheromone diffusers, 3 litter boxes for 2 cats... etc. You name it, I've tried it. I work in a pet store and am pretty knowledgeable about cats, but I am at my whit's end with this one. He IS fixed and it's not U.T.I., he's been to the vet over and over again. Please, any serious ideas will be appreciated, I love him to death, yet my patience is being sorely tested.