Starship Troopers changed how I think about a lot of things... especially the right to vote and earning your way into adult society. I thought the movie was a complete waste of time.

Try The Moon is a Harsh Mistress also by Heinlein. The moon is a penal colony and they revolt against earth. There is a lot of story there, it is also one of my favorites.

Also try Harry Turtledove. He does alternate history and he has at least one series that totally sucked me in. The Darkness series is World War II, but with dragons instead of planes and leviathans instead of subs and elephant/rhino-ish things instead of tanks. Mages instead of weapons creating scientists... it is an amazing series with lots of character development.

Getting back to Heinlein, there are some like Glory Road that take a military main char and use his training to carry the adventure story, Between Planets which has a galactic war, Starman Jones which has a teenager with a passion for astronomy saving the day and Citizen of the Galaxy which has a boy slave and space pirates...

Heinlein was in the Navy, and uses his military insight to flesh out a lot of stories... him and Turtledove can keep you reading for a good long time :)

I enjoied the Halo series, but sadly that's the only Military Sci-Fi I've read. Although the ENTIRE thing is five books long, it's very easy to scoot by on several smaller combinations.

The best way to go is by publication order, NOT chonologically. You get more dropping-off points that way. The first would be The Fall of Reach. If you don't like it, you can stop there pretty safely. If you DO like it, finish the origonal trilogy: The Flood and First Strike. If you're still enjoying it, Ghosts of Onyx. Finish with Contact Harvest.

I've read a fair number of books based on video games. They don't have a good reputation, and with good reason a lot of the time. But Halo is ~good.~