I've read every single book, up until 2 years ago, when work took over my life.
I've used all the Fictionwise offers to fill up my Sony 505 with around 50-odd titles that I'd missed.
It's worth saying that the current titles are overall far better than the majority of the earlier titles. The great draw to the newer titles are the very good continuations from the end of the televised series.
Recommendations are in order of preference :-
DS9 - Every book set after the end of the series
New Frontiers - An acquired taste but always a fun read
TNG - Start with a Time To...series and the current novels set after Nemesis, starting with Death In Winter
TOS - Rihansuu series and the Errand Trilogies are standouts
To get a feel for the books and series available and synopsis, I find this the best resource
http://memory-alpha.org/en/wiki/Pocket_Books