When it comes to locations, I'm one of those crazy authors who has to see it, touch it, taste it, before I trust myself to recreate it for my readers. Having said that, visiting a locked-down pediatric psych ward was the most intimidating research I've ever done - and I've visited maximum security prisons, shooting galleries, bone collections, etc.
Before I became a suspense novelist, I wrote romantic suspense as Alicia Scott.
I still like the relationship part of any story. You don't want your character to figure everything out and then at the end of the day, go home and eat soup from a can by herself.
When I got my very first phone call that I'd hit the 'New York Times' list, I had a small rush of 'I've made it!' But the next morning, it occurred to me I didn't know what it was, so I called my agent and asked what being a 'New York Times' bestselling author really meant. He informed me that I was now a thousand pound gorilla.