There's several I can think of:
1) War of the Worlds (1953): how long did it take the Martians to start dying, and when did the last invaders arrive? Then there's picking up the pieces afterwards, likely turmoil in the Soviet Bloc, French and British Colonies declaring independence-and not much that could be done about it, trying to reverse-engineer Martian tech, etc. (and how would we know they were Martians?).
2) Countdown to Looking Glass (1984): Did the Superpowers go down the slippery slope to general war, or did cooler heads prevail?
3) Amerika (1987): What happened after the Battle of Milford? Did the spark of revolution start to spread, despite what the Soviets were hoping?
4) By Dawn's Early Light (1990) Several things here: Did the Soviet Union come apart-and how bloody was it? Fighting in Europe-conventional, nuclear, or a bit of both? Situation in the U.S: Martial Law, perhaps? And how to bring U.S. forces home from overseas to help in rebuilding?
5) V (the TV series, 1984-5): What happened after the cease-fire? Since the Leader initiated the cease-fire, he's understood that the war on Earth has gone very bad, and that there's no chance of an outright victory and his forces are being bled white. Earth's terms for a peace agreement are likely to be very serious from the Visitors' POV, but returning the people who were "processed" into cold sleep for eventual consumption/breeding/slave labor, reparations for the material damage (destroyed cities, infrastructure, etc., and return of the water (if possible). And how would the peace be kept? Earth's military forces are likely to start thinking about turning the Solar System into a fortress so that it never happens again-even if it means using captured/transferred Visitor tech as a basis for going forward.
6) War of the Worlds (2005): Similar to 1953 in many respects: post-invasion conflicts are a certainty, rebuilding is going to take a while, and then there's trying to find out who they were, how long were those tripods buried, and are there more, just waiting? And how fast can we get back into space to at least have some early warning?
7) Battle: Los Angeles (2011): The Battle in L.A. is turning in the Marines' favor, but it's going to be a tough slog. Same thing in the other invasion sites. Now, who are the invaders? Where are they from? We know what they want-our water and us out of the way. Do they have ships in orbit or past the Moon, still watching and waiting? And after the invasion is defeated, what's next?
