Hey Yasmine! Love your OW series and am so looking forward to Night Myst!
As for other authors with multiple series, I go both ways. Love everything Sherrilyn Kenyon writes and keep up on all her series. Laurell K Hamilton, I love the Anita series and have tried the Merry series but for some reason couldn't get past book 2 on that one. Jim Butcher also fall in the later category. Love the Dresden Files but haven't even tried his Sci-Fi series....it just seems too much outside the box for my usual reading.
Anyway keep up the great writing and I'll keep reading! :)