It freezes really well once cooked - if you like the soups, you can roast a bunch, scoop it out of the shell, and freeze for later use.
For soups, I quite like curry-like seasonings; spices like cumin, coriander, cardamon, cinnamon, cloves, turmeric, plus garlic, ginger, lemon and onion. Or go for sage and thyme (fresh or dried), and a little bit of cream drizzled over the top when it's finished.
I quite like Japanese squash nimono - the squash is cut into pieces and simmered in a broth of soy sauce, mirin (a sweet rice wine) and dashi (a fish stock). It's a lovely balance of salty/savory and the natural sweetness of the squash, and it's how I do squash for Christmas dinner.