I would look at mainstream bookstores and buy books from academic presses. Regular bookstores (think B&N) usually stock "popular history" that's more accessible and engrossing than textbooks; buying stuff published by university presses gives you a better chance of the work being thoroughly fact-checked and edited for accuracy.

It massively depends on what you're looking for - in general, you're stuck with full academic works or immensely accessible books written specifically for the general public. A good medium might be text books written for undergraduates (many universities publish their required reading lists online!), as they cover subjects in reasonable depth and also show what other books/articles you can read next.

New, exciting and innovative research takes far longer to find a written foothold. During conferences new ideas might be proposed, but an article in an esteemed journal will take anywhere from a few months to a couple of years. A book or a monograph will be even longer in the making. There are some good podcast series and Twitterstorians, which might also be interesting and relevant to your interests, but due to length, don't have the room to discuss anything in depth.