I think virtually any of David Gemmell's
works could be adapted as a movie fairly successfully.
The reason for this is that despite being my favourite author his plots are essentially simple... and with his later works to the point of derision. Almost without exception there is a small group of heroes consisting of a grizzled, veteran warrior (who may or may not also be one of the world's greatest swordsman), a young, inexperienced, adventurer, a big, blunt warrior who is rough around the edges but has a heart of gold (and uses a big axe), a naive, moral centre of the group (who may turn into a warrior priest), a love interest (who either provides the moral centre or the target of the quest) and a more swashbuckling ladies man/charmer (who often turns into the archer). This group are on a quest that requires them to travel through a hostile/enemy controlled area while possibly being pursued and normally ends in something resembling a siege.
Along with the plots the themes are fairly consistent and simple. The grizzled warrior finds some form of redemption, the young adventurer has a great realisation but is never jaded, the rought around the edges man with the axe commits a great act of heroism (possibly unexpected) and in general it's about loyalty, sacrifice, honour, human will and friendship.
And in perhaps the biggest nod to a Hollywood adaptation there's virtually always a big set piece. Often this corresponds with a siege but for others it's even more strange/evocative... a novel built around a post-apocalyptic Western theme ends with the Titanic sailing through the sky before sinking or a nuclear bomb being sent through time or King Arthur marching the lost Ninth Legion through the mists of time...
Some fantasy novels simply work far better as TV adaptation than a movie... Song of Ice and Fire is the clear example as the 90-120 minute time limit of a movie simply isn't enough time to develop the varied plot points. Gemmell novels are the opposite. They're the summer blockbuster of fantasy, the popcorn film of novels. You can normally see what's going to happen before it actually happens, you know the themes, you know the characters... but you read along anyway because it's so damn enjoyable.