okay i've been thinking about this one for a WHILE but i think i got it down.
i think gale's favorite would be 2001: a space odyssey. i think he enjoys 1) older films that fulfill an interest in sci-fi and 2) movies that are generally more scientifically accurate than most. gale is the type to pick apart a movie, whether for appreciating details or pointing out inconsistencies/inaccuracies to the point he's yapping throughout the movie and it makes lupa a bit frustrated (he's like, "it's a movie babe...")
lupa's favorite is life of pi. he loves philosophical movies and debating them with gale. actually i can see them enjoying movies together in the most unconventional way of just having arguments about them.
but ultimately yes they are having a movie date and they're cuddling with glasses of wine in their hands :)