Cook up a few pies for the family, your church group or bring one to work. Similar to pumpkin pie (I like it better.)

You can either just blanch and freeze as-is, or process further into products such as sweet potato fries, mashed, etc. and then freeze.

You can then serve as is or use for casseroles or make pies/breads.

But it does take a long time for them to go bad, so you might want to just keep using them up and not bother with all that.

Rot is the culprit. Cull or trim and cook any that are off. The other ideas above are good ones, as well.

you forgot bake.

Oven fries (coat wedges with oil, bake) or regular French fries

Stir-fry chunks in peanut oil

Empanadas

best sweet potato casserole EVER -- http://allrecipes.com/recipe/gourmet-sweet-potato-classic/

sweet potato biscuits are a big tradition in some locales -- I've only made them once, semi-successfully -- http://southernfood.about.com/od/biscuitrecipes/r/bl90321i.htm

Just Google "recipe sweet potato" to find lots more. Sweet potato soup is surprisingly popular, and there are a variety of recipes -- I've made this one once before: http://www.simplyrecipes.com/recipes/creamy_sweet_potato_soup/

Here's an interesting use for sweet potatoes (& carrots) as a fat substitute in other recipes: http://low-cholesterol.food.com/recipe/sweet-potato-carrot-fat-substitute-for-recipe-347628

Here's an interesting sweet potato sandwich: http://upload.democraticunderground.com/1018122547

Cubed Sweet potatoes go remarkably well in Chili. You can do it with meat or without--just add to your regular recipe. I add par cooked boiled sweets. If you want a sweeter flavor you can add roasted closer to the end of your chili simmer.

It's very Yummy and Chili tastes even better as left overs.

I don't remember if anyone mentioned biscuits but sweets are wonderful in doughs.... Just google for a recipe. I don't have a tried and true.

My usual Thanksgiving dish is layered sweets/apples/and Candied Pecans. This is great with blue cheese or sharp cheddar either served on the side or in a flour/butter/ cheese crumble on top

If you can keep them in a cool dark airy place you should be able to keep them for several months