SM64 was, and still is, one of the most awesome games in existence, with one of the best musical scores ever, blow-away variety, and grahics and gameplay that set a benchmark throughout game history. It's impossible to go through game history properly without mentioning Super Mario 64.
Sunshine had a story, well, a bit beyond "rescue the princess". It also, as mentioned, had a common "theme", no gravity-defying islands, blocks of water that suddenly stopped, leading unlucky swimmers into an eternal plunge, and it looked, in a Mario way, sensible. Well, save from the Sky and Secret levels, that had everything the rest of the game lacked in WTF-factor. Delfino Plaza does make sense, Ricco Harbor is a major port, and there are no remote, faraway places habited only by Bowser's evil minions. Only perfectly valid holiday places. The graphics were sweet, and the chill-factor at the max. I could spend quite some time just cruising around, practising awesome jumps or ways to get from one place to another in shortest possible time. The levels weren't missions set on a stage (like Galaxy is), it's a stage with a mission within. You are free to roam the area in most levels, not necessarily follow a set path to the finish. A bit like SM64, only even freer. And with sense. No snow levels, though.
Galaxy was epic. Simply epic. Blowaway galaxies, epic music (Oh, the Good Egg Galaxy), vast panoramas of stars and planets, and an athmosphere challenging even Sunshine.
However, the roam-factor was next to none. You couldn't fly freely around, explore another rock, fly further, look at a place and think "you know, I'll go see what's there. Wonder how I can get to it?", like in Sunshine. You were usually given a set path to follow, and there was no room for leaving that path. I want to explore the Dreadnought, fight my way through the Battlerock, explore a cave in Freezeflame, relax at the Beach Bar in Beach Bowl, and lay down and look at the sky from a veranda on a little house in Good Egg (I know there is one, but no veranda).
There were also next to no "sense" in that sense that there are no places where natives live, no towns or cities, no hospitality. Just wilderness, obstacles habited solely by random enemies. In Sunshine, the enemies either originated from the evil present (the goop monsters), or they were native to the area (e.g. the Plungelos), in Galaxy, they fit with the theme, but no one knows where they come from or why they are just there, waiting for an enemy to appear. Also, gravity is on the loose (and we love it!). After you have gotten all 241 stars, however, you have quite little to do.
Overall, 64 gets it for me. I never owned it myself, but my cousin did. I remember I used to sleep over at his, we slept in the living room and got up before sunrise to give "that star" another try. I remember getting to Tick Tock clock for the first time, finally beating Bowser, learning the secret of the pyramid, beating King Boo in the haunted mansion (of which SMG's is a pale copy). Following next is Super Mario Sunshine, for the relax factor, third, but in no means last, is Super Mario Galaxy. It's purely epic, and a lot better than most other games around (Or I have played too few. Who knows).
And coincidentally, my current piano project is learning all the Main Hub songs by heart. I know Inside the Castle and Rosalina's Observatory by heart, only Delfino Plaza left. thanks for arranging, guys!