Twilight Imperium, really? I only played it once and it was the longest, most boring experience. Each turn just takes an enormous time, almost as long as a Warhammer 40k turn and I played with 5 other players. When you were done with your turn you could go for a really long walk and when you came back you wondered how the hell they just finished 2 turns...
I really really enjoy boardgames, but not ones that take a weekend to play...
(this isn't meant to insult you, I am just seriously wondering if my experience with it is a lot different than yours or if you like boardgames that you play an entire weekend)