How about:
Lensman, E.E. "Doc" Smith
I'd second that; great example of early Sci Fi!
and, in many ways, the initial source material for Starfire. The later works by David A Kyle are in the process of being read (They're not as immediatly engaging as Grey Lensman - my first ever SF book)
I always liked "The Forever War" (Joe Haldemann), and its antithesis "Starship Troopers" (R.A.Heinlien).
I liked some of the early Honor Harrington books, but havent really enjoyed as much after "Honor Amoung Enemies" as HH and the politicos have become more two-dimensional and the Kingdom relies more on luck than good planning in the campaigns against the Havenites.
I liked the first two books in the NIght's Dawn trilogy, but the last book ended us too much as a Deux Ex Machina for me. It was a bit like the effect of reading Pournelle's Footfall when I got to the last page!