Glad you liked the book! Always a pleasure to please an audience.
I have to admit, I haven't read any of your other works. But, since I know you're a regular customer here, I'll be certain to check some more of your Who novels out...
Others here can probably tell you which are best, but I'd say this about them all:
White Darkness- first novel, with all that entails
First Frontier - Has a twist
Sanctuary - is written in a deliberately dense style to evoke a certain antiquarian tone. People who get that love, people who don't just assume I can't write and did it by mistake.
Lords Of The Storm - helps if you've seen the Sontaran episodes
Shadow Of Weng Chiang- Helps if you've seen Talons
The Dark Path - you've read already, but for the benefit of others, it's somewhat continuity-heavy
Face Of The Enemy - The Master and the Brig are the stars, but it is very continuity-heavy. But for once necessarily so
Mission Impractical- Fanwank overload, with Frobisher the talking penguin
Wages Of Sin- Shorter and more character based, about Rasputin
Autumn Mist - middle one of an EDA trilogy
Bullet Time- Helps if you've read First Frontier, but not necessary
The Eleventh Tiger - works on its own.
I'd recommend: Sanctuary, Wages Of Sin, Bullet Time and Eleventh Tiger to everyone, and Shadow Of Weng Chiang, Dark Path and Face Of The Enemy to folks familiar with the original show.
Away from Who, I'd recommend Destination Zero as a modern action thing, and Twilight Of Kerberos - The Light Of Heaven for being the most recent.
And don't forget to check out the William Shatner stuff on Saturday, Free Comic Book Day.