I ended up not getting Secret Garden because the crowded, tiny shapes aren't relaxing for me; I like larger areas so I can do shading, texture, etc. but that's just me.

Me too so it's not just you, Summerfun! :-) I highly recommend Angie Grace's books and I've got my eye on Jenean Morrison's Mandala book. Angie Grace's books are all one sided so they work great with markers. I use Bic Mark-its - great affordable option to Copic and other expensive art markers.

There's art markers and pens, which are much finer detail, for those small detailed books.

Stabilo Fineliners are excellent for details and economic as well. I got a set of 30 for under $30.00.