I walked this path. Think about where you want to be when you're done. Are you married? Do you have kids? Do you want to do those things? If you want to be an academic, you have at least a decade of grueling work ahead. That's 4 years to do the Ph.D., and another 6 to get tenure, which is like doing three more dissertations worth of research while trying to manage a small group of young, inexperienced engineers. And that's if everything goes well. Precious little time for a spouse and kids. Ignore this ridiculous talk about learning to golf and taking vacations abroad. Nobody I know did that.

Personally, I finished the PhD in May and moved on to a really fantastic job in my field. I have time and money that I wouldn't have as an academic.

I'd like to clear up a few misconceptions I had about the academic lifestyle going in. This is about the professor job, not grad school.

1. Being a professor is not about teaching. I went into grad school thinking I could make a difference. Address the rampant gaps in my colleagues' education. It turns out that professors generally abhor teaching, and that departments actually use teaching assignments to punish underperforming faculty. Performance means papers and even more importantly grant money. Teaching doesn't enter into it.

2. Professors do not have any free time. Even tenured ones. That appealing academic calendar is a mirage. If you are a professor, you're a professor every waking minute. You spend your vacations at conferences, your summers trying to get ahead on research. You read papers before breakfast and after dinner. Or you burn out after getting tenure, get a heavy teaching load as punishment for your lack of productivity, and turn into the kind of professor everybody has an anecdote about. The one with nutjob politics who never turns up for office hours, or the one who lectures while hung over or still drunk.

Sorry to rant, grad school is no picnic and I wish I'd gone into it with my eyes wider open. I'm happy with the end result, personal growth, seeing things on a higher level, being "doctor" so-and-so, having an awesome job, but it's not at all an easy way out if you're tired of what you're doing now.

If you want a CS Ph.D., demonstrate that you're a REALLY REALLY GOOD programmer; that can make up for lack of significant research experience. I've advised a few dozen students of various ranks, and I still rate programming ability as amongst the top prerequisite ... everything else can be learned more easily in a short time, imho:

http://pgbovine.net/prospective-students.htm

I did a MEng in CS, then went into work in a totally different industry for four years where I hardly touched a computer, and managed to come back in to do a PhD in CS without any research experience.

I literally cold-emailed some potential advisors that I found from looking at university websites and told them what I was passionate about. I got asked in for an interview and pitched what I wanted to work on.

I think if you are grown up and passionate about doing a PhD you are already going to look pretty impressive, as most advisors will usually be dealing with young undergraduates who can often be drifting into a PhD without really knowing what they want.

Someone dumping a paying career they have have already invested most of their 20s into has obviously thought about it very carefully and knows what they want.

Find a topic you like and mail some people in the field directly. If you make it personal you'll probably get a response. I've finished one PhD and dropped out of another. In both cases, it started off with a friendly chat with my potential supervisor.