[Lion of High Park]

I completely agree about the MYTH series. Very clever, very enjoyable reads. I had never heard why the series stopped, but was disappointed that no more books were forthcoming.

As for other titles/authors:

Larry Niven, Ringworld, Ringworld Engineers, etc.
Niven/Pournelle, Mote in God's Eyes (an absolute classic), Lucifer's Hammer, Inferno, Footfall, etc.
Kim Stanley Robinson, Red/Green/Blue Mars series, utterly brilliant
Piers Anthony, Xanth series
Arthur C Clarke, pretty well everything he's written
Stephen Donaldson, Chronicles of Thomas Covenant series,
Tolkien, of course
And, just for a fun change of pace, the original Ian Fleming Bond books (so much cooler than the movies)

Just my 0.02$