Harrington novels are good for interstellar war, if you like the grunt level, I recommend the Valor series by Tanya Huff. If you like mercs, the Star Risk series by Chris Bunch is good. Or the Miles Vorkosigan series...
But I think the most Travelleresque series is still the Liaden Universe by Sharon Lee and Steve Miller.
http://www.korval.com/liad.htm
Title of the Book: Scout's Progress
Author: Sharon Lee, Steve Miller
Part of a Series (Y/N): Y (7 books) (4 other novels in same setting)
Description: This tells the meeting of Val'con yos Phelium's parents.
Title of the Book: Local Custom
Author: Sharon Lee, Steve Miller
Part of a Series (Y/N): Y (7 books) (4 other novels in same setting)
Description: This tells the story on Shan yos'Galan's parents, one of whom is a Terran (gasp)
Title of the Book: Conflict of Honors
Author: Sharon Lee, Steve Miller
Part of a Series (Y/N): Y (7 books) (4 other novels in same setting)
Description: This tells the story of Shan's meeting with Priscilla Mendoza, a Terran from the planet Sintia.
Title of the Book: Agent of Change
Author: Sharon Lee, Steve Miller
Part of a Series (Y/N): Y (7 books) (4 other novels in same setting)
Description: This tells the story of Valcon, a super James Bond (Agent of Change), and his meeting of Miri Robertson, a Merc.
Title of the Book: Carpe Diem
Author: Sharon Lee, Steve Miller
Part of a Series (Y/N): Y (7 books) (4 other novels in same setting)
Description:On the run from assassins, Val Con yos’Phelium and Miri Robertson are stranded on a distant planet and must learn to trust each other if they’re going to survive...
Title of the Book: Plan B
Author: Sharon Lee, Steve Miller
Part of a Series (Y/N): Y (7 books) (4 other novels in same setting)
Description:Clan Korval is under attack from the Dept....
Title of the Book: I Dare
Author: Sharon Lee, Steve Miller
Part of a Series (Y/N): Y (7 books) (4 other novels in same setting)
Description:The current end of the series, but you can get a preview of a further story at:
http://www.korval.com/fledgling/
Or the other books...
Title of the Book: Crystal Soldier
Author: Sharon Lee, Steve Miller
Part of a Series (Y/N): Y (2 books)
Description: Centuries in the past, mankind fought a seemingly unbeatable adversary from sector to sector across the Spiral Arm until the war ground to a standstill and the Enemy withdrew. Believing that they had won, the citizens of the galaxy rebuilt. The Inner Worlds, which had escaped the worst of the war's ravages, became even more insular, while the Rim worlds adopted a free and easy way with law and order. Now, hundreds of years after their withdrawal, the Enemy is back - and this time they'll be satisfied with nothing less than the extinction of the galaxy.
Title of the Book: Crystal Dragon
Author: Sharon Lee, Steve Miller
Part of a Series (Y/N): Y (2 books)
Description: The sequel to Crystal Soldier, Cantra 'yos Phelium, a shady free trader, teams up with M. Jela Granthor’s Guard, an elite soldier, to defeat the Enemy and lead the founders of Liad to a new beginning.