Good wholistic books about retirement planning?

I've been working for a TPA/Recordkeeper for a good 6 months now and I'm absolutely loving it. I'm definitely learning a lot as I go from my boss & coworkers, and I'm quite knowledgeable about the plans we work on, but we have a fairly narrow scope. Currently we only ever have done DC 401k & PS plans, most of them safe harbor, all of them quite similar in the grand scheme of things. That said we're running into more and more instances where it would be nice to have a good understanding of other types of plans and various fundamentals outside our usual operations, and I'm also someone who likes to really invest in what I do and become an expert. Are there any good books out there that break down the ins and outs of anything related to the retirement planning industry or DB/DC plans, or otherwise good resources written in human-readable language?

I'd suggest looking up the pension organizations that give us all the fancy letters after our names, and explore their education offerings.

(ASPPA/NIPA to name two to start with)

Tbh, I find the IRS website to be quite a good read :) I've probably visited every page that's remotely retirement-related at least 100 times. If you start clicking around here and here you'll find lots of links to other useful info. The DOL/EBSA site also has some useful resources, though they're not updated as often and their site is laid out less intuitively (imo). I've also read through the relevant sections of the actual IRC and ERISA several times, but I wouldn't call those human-readable (though I learned more from those two texts than I have from anything else). 

I found two main issues with using books or operational guides as a source of information:

(1) the law changes all the time, so the guides are very quickly irrelevant, and

(2) the law doesn't actually dictate HOW you have to run a retirement plan, it just tells you what requirements must be met. This leaves a lot of room for creative solutions, which is probably why you've enjoyed your job so much :)