I would second the thoughts above that IT can be a pretty dreary pursuit.
Agreed, don't go into IT unless you already live and breath it as a hobby, or you're going to hate it right out of the gate.
If you do go for it, I agree that certifications do not meaning anything. I don't think I've ever considered certifications on an applicants resume. They're too easy to get and tend to be flashed by those with no actual experience, so it kind of has the opposite effect of what you want. A degree means something for entry level, but beyond that I don't even care about the degree. I just interviewed a guy yesterday that had 15 years of good IT experience and no degree and I congratulated him and told him that was awesome. He said I'm the first person to see it that way, though.
If you want to go to school and you want to get into IT, then go to school for IT. Otherwise I'm not sure I'd distract myself. My degree is in accounting but I worked my way through school in IT and by the time I graduated I would have had to take a step back in pay to use my degree, so other than one job I had at a smaller company where I did dual duties I haven't used my degree. Whereas a buddy of mine that started in IT about the same time as me but didn't waste time going to school got ahead of me. We do pretty much the exact same thing now, but I've never caught up to him in pay.
You can get into IT without education, like others have said, depending on what you're interested in. Sys admin? Get a spare computer, install windows server or linux, get a domain name and point it towards your home IP and build a website and start running your own mail server and dns. After that's going build a database backend for the website. Can be anything, wordpress, etc. You now have the big 4 on your resume. In Linux those being Apache, Postfix/Sendmail, MySQL and Bind. MS has their equivalents. Or for a bonus line item forget the spare computer and do it all on Amazon and you can add AWS to your resume. You're not going to get a 6-figure job after that but you'll squeeze your foot into a door.
Want to be a coder? I'm not one, but from what I've seen that's even easier to self-start, there are so many resources out there. One of the junior devs we hired at work last year got the job because he had some decent self-driven projects. He had no work experience, this is his first.
Yes you will probably have to start at the bottom but if you live and breath IT you will learn quickly and move up. I started in tech support which is a common, albeit shitty, first step. But you do have to really enjoy IT.
Accounting is fun if you find it fun. Attention to detail and an affinity for coma-inducing reams of figures is required. Businesses run on finance, at the end of the day, so financial wizards can have fun and create a great deal of value. Or just count beans.
I'm one of those weird people that loves numbers and accounting. If you want to do accounting because you enjoy it, then ignore IT and everything I said above. Since you work nights and weekends you will have an easier time getting an internship during normal business hours. Don't waste time in IT to the detriment of gaining accounting experience, like I did.
As to your question about corporate jobs, I prefer small companies as they tend to have less red tape and more varied days, but in every job I've ever had by far the #1 most important thing is coworkers and my supervisor, and those can be good or bad at any size company, so that's not at top of the list of things I care about in a job, personally. But like others have said, just because you're a CPA doesn't mean you have to go work for the Big 3 (is it still 3?).