About ender's series:
If you liked ender's game (book), you might also enjoy ender's shaddow. Is written more or less like ender's game but it focuses on Bean's actions (it's a paralel ender's game book).
IMHO, the sequels of ender's game where also great, even though not as action centric as the first book. I liked how the characters interacted.
But the last book in the ender's series... nope... did not liked it.
And in the shaddow series, except the Ender's Shaddow, all are a little bit boooooooring... annoying... and so on...
I am curious about G.R.R.Martins. Fantasy, AFAIK. But be warned: if you touch fantasy, you might not be able to stop! (I know, because I like anime&manga&SF and after starting the fiction books... I cannot stop anymore from reading.
I would go for Dune, the original ones.
)