I must say that the best series that I have read is the series by Megan Whalen Turner.
It comprises four books:
The Thief
The Queen of Attolia
The King of Attolia
A Conspiracy of Kings
They follow the adventures of Eugenides, a master thief and although the time period is similar to ancient Greece, the book takes place in a Byzantine-like civilization that includes more modern inventions such as glass window panes, pocket watches, telescopes, and printed books.
The plot, and characterisation are exceptional, and the interesting twists in the tale will keep you riveted. Seriously.
Buy these books. They are excellent.
The Darktower series is also very good, although it is rather heavy reading, and I found myself struggling to keep track of the various multiple realities and storyline. But if you have lost of time and concentration, go for it.