I switched from software development to law and am quite happy so far. I liked tech, but my job involves a lot more writing and personal interaction and that suits me. But I've met people who made the same transition and disliked it for precisely those same qualities. Even desk jobs vary widely in character and its worth introspecting to figure out what suits you best.
I think going to school is a great idea. I was too young to appreciate the unique social context of school when I was an undergrad, but after working for a couple of years I approached grad school very differently. School is really a wonderful place to meet intelligent people with diverse interests. It's a wonderful setting for dating and having relationships. It's a real opportunity to figure out what sort of work you'd like and enjoy. Especially for someone coming back from the working world, it's an opportunity to change your scene and explore things that make you happier. Yes, it's expensive and time consuming, but I think it can also be tremendously valuable for reasons that have nothing to do with jobs.