I went back to school and I double majored in CS and mathematics and took the hardest courses I could. Here's the rub, if you want to go back because you feel like you have some gaps in your knowledge and want to fill them in, college can be great for that. I specifically felt weak in math before I went, so I studied it specifically.
You'll be at a big advantage in a lot of the CS classes because many of your peers are starting with no programming experience, so the more programming heavy ones will probably be comparatively easy for you. So focus on more theoretical stuff if you go.
Also, keep costs in mind. While you're at school your good salary means the opportunity cost is fairly steep. If tuition is high too it's very expensive. I went to an in-state school, though I'm fortunate that the local school has a strong program.
In terms of the opportunities it provides, my previous experience as a web developer meant that I got more interest in that arena than in other areas, but the difference was stark. Maybe the economy changed while I was studying, but it went from sending out a ton of resumes and getting a small handful of nibbles to 'if I send out a resume to a job I'm even reasonably qualified for, I'll get an interview.' It was that stark.
Money wise (at least short term) I'm still behind because of the opportunity cost, but I learned a lot and can pick a better quality job, so for me it was worth it. It's a personal decision though. In your case you can send your resume to Silicon Valley first and see if you get any bites, if that's what is more important to you.
I agree with the Math, I have been practicing Oxford CS & Maths entrance exams (I don't intend to go to an institute as "high" as Oxford, but I set the bar for myself quite high) and have been routinely scoring much better for the logical and riddle based exercises than the Maths and have recently been practicing my logarithms and linear algebra where I feel I am lacking (or at least weaker than my other areas)