They brought me in for a total of ~20 hours of interview, and in that time I discussed work-related topics with every single C-level. I went through a standard interview with questions, and then a longer skill test that included every current engineer at the company.
For the last few hours they paired me up with a current engineer to work on some database issues they'd been having.
I've been very happily employed here now for around 7 months, and after adding this company to my resume I've had quite a lot of offers on LinkedIn. I feel nothing other than "Oh, this company has offered me an interview, that's really cool!" towards these offers.
I think it's one of the best things in the world to have that feeling, and I wish everyone who was hired in an engineer position felt the same way.