Tom Clancy and Stephen King are my favourite authors, and I did like Mr. Clark. I loved the Rainbow Six novel and though I haven't read them all, I also love the novels starting with The Hunt for Red October. Awesome read.
I haven't read Without Remorse, I don't think, but he appears in The Sum of All Fears as well, I believe.
I started Without Remorse at one point but don't think I finished it. Actually, I don't think I've ever finished a Tom Clancy novel. Probably because I haven't tried to read one since I was twelve (not the level of reading but the length that always got
me back then haha). Good books though, need to pick one up again when I have time.
There are parts of all his books that I think he goes into waaaaaaaay toooo much detail about s*** I would have to go to an 8 yr graduate school to understand. Lol. Those parts can also drag a little but he is a great writer and evokes some pretty good emotion.
You should def give Without Remorse another go.