The new components and improvements in Lost Treasures makes little play difference, especially in large games. However, it has new colonization events, and it really adds more flavor to the game, what with the secret weapons and special facilities. I recommend it if you enjoy the, er, 'role-play' aspect of the game. If you just want a different play experience, it may not do much for you.
Rise of the Terrans is ok if you like building ships (like me), but most of the focus is on the once-and-done campaign. If you like campaigns or follow the game's narrative, I imagine it is a must. If you are in neither category, I would skip it. Altarian Prophecy is a repeat of the same, except you get one additional ship style.
