For sure I'm forgetting some but the core of my box-set collection is
all ST sets (TOS, Ron Jones, Giacchino de luxe, whatever) all LOTR trilogy Complete Recordings Herrmann at Fox Goldsmith at Fox Fantasy World of Irwin Allen Indiana Jones box set Arista SW trilogy the fantastic and mammoth SW trilogy Original Radio Drama (15 or 20 CDs? I don't remember) both X-files sets Superman blue box Friday 13th Karate Kid (do BSG, Omen, Twilight Zone, Goldsmith Final Recordings box sets also count?) Spartacus MoH Lethal Weapon Elfman/Burton zoetrope box HP and the Deathly Hallows set the gorgeous Cowboy Bebop music box set some "le cinema de composer X" box set (X = Jarre is my favourite)
etc.
and the weirdest soundtrack box I have is Nightmare before Christmas in Jack Skellington head-case
Box sets are fantastic, even if expensive. I currently own: The Lord of the Rings Complete Recordings (minus Two Towers, which I recently sold for college $) Possibly all of LLL's: MOH, Friday the 13th, Star Trek, both volumes of X Files Varese's Conti Boxes - Karate Kid, North and South Books 1 and 2 FSM's Star Trek: The Ron Jones Project and Superman Box
Star Trek TNG Ron Jones - FSM Star Trek TNG Volume 1 - La-La Land Star Trek DS9 Collection - La-La Land Karate Kid set - Varèse Indiana Jones set - Concord Star Wars The Original Trilogy Special Editions - RCA Star Wars The Original Trilogy Anthology
I did have the Superman FSM Blue Box but gave it away. I'm thinking about buying it again though before it sells out.
For the Star Wars OT S.E. sets they are the original ones with the holographic CDs.
Although not sure if this considers "box set" or not... but I also have
Star Trek The Motion Picture - La-La Land Star Trek II The Wrath Of Khan - FSM Star Trek III The Search For Spock - FSM Star Trek IV The Voyage Home - Intrada Star Trek V The Final Frontier - La-La Land Star Trek VI The Undiscovered Country - Intrada Star Trek Generations (Complete) - GNP Star Trek First Contact (Complete) - GNP Star Trek Insurrection (Complete) - GNP Star Trek Nemesis (Complete) - Varèse Note: Coming soon Star Trek 2009 both OST and D.E. - Varèse Star Trek Into Darkness OST
Godzilla Perfect Box Set Collection (1-6) Herrmann at Fox Miklos Rozsa Treasury FSM MGM Black Box Elmer Bernstein Filmmusic Collection Box Lord of the Rings Complete Collection (1-3) Laurie Johnson Box Collections (3 boxes so far) Herrmann Suites (Varese Box Set) Tiomkin Columbia LP Box (a beautiful set of lps from France with Fall of the Roman Empire, 55 Days at Peking, The Old Man and the Sea, The Alamo, The Guns of Navarone, Wild is the Wind) Elmer Bernstein Unused Score Box (Varese)
To be honest, I really don't care for multi-film box sets because, more often than not, I have to buy stuff I don't want in order to get the stuff I do want. I bought the Superman and Lethal Weapon boxes even though I wanted only the first score in those respective film series. The Indiana Jones box is a greater value to me because I love three of the four scores with that set. The only box set where I did want absolutely everything is the LLL ST:TOS television soundtracks. Price was no object on that one.
I much preferred the Star Wars and Lord of the Rings individual releases (even though I did want all of those scores!).