I have to say I've been reminiscing about Super Mario Galaxy quite a bit lately and I'm also really looking forward to Super Mario Galaxy 2. As fulfilling as the first one seemed, I've recently had the feeling that it never came full circle, as if two years after finishing it, it still seems to have a lot of potential. I guess it's a good thing there's a sequel, then.
I remember longing to play it again last winter as well. I think I sometimes get seasonal nostalgia for games I played at some period during the year. Every autumn I have to play Advance Wars and/or Fire Emblem, and I'm in heat for Resident Evil and Metal Gear Solid in the summer.