I thoroughly enjoyed Empire (did I suggest that to you, RockPile? I don't remember...I've recommended that book to many people). Glad you liked it, anyhow. Card is one of my favorite sci-fi writers.
The high tech stuff was a little bit outside the realm of modern capability, but I thought it was interesting, nonetheless.
I just finished re-reading Arthur C. Clarke's "Rendezvous With Rama" last week. What a freakin' awesome book that was. I'd forgotten how good.
After my checkride this week (that I'm studying for...really), I'm starting: