"Templar" series by Jack Whyte.
I finally got around to reading the first two books of the "Templar" series by Jack Whyte (first book is "Knights of the Black and White", second one is "Standard of Honour", third one comes out in November), and I quite enjoyed them. They are historical novels, meshing fact and fantasy, dealing with the "Holy Grail" and the Templar Knights. I had read some of Whyte's Roman novels before, and I always liked his style. The first 50 pages were a little slow, I found, but the story and pace pick up. I often looked up names and events at Wikipedia, because the novels sparked my curiosity and I wanted to know more, so it's also been quite educating.
It's actually not my usual genre (mostly a fantasy reader), but I like the whole Templar myth. Can only recommend the two books, and probably the third one too when it comes out next month.
Re: "Templar" series by Jack Whyte.
I've just read the first Templar one as well; picked it up at a boot sale recently when I was back in the UK for a visit. Not bad at all, but not sure yet whether I'll read the others. I'm still thinking about it.
One I can recommend for a good mix of history/fiction is Dinah Lampitt's "The King's Women". It's a twist on the Joan of Arc story with the Knights Templar/Priory of Sion behind the plan/plot. If you go to usedbooksearch.co.uk, you'll find a few outlets selling it cheap as it's quite old now (published back in 1993).
Like you, I'm a fantasy fan mostly, but have always been curious about the Knights Templar story. I'm also a follower of all things curious about the Priory of Sion, ever since the books came out.