I'm among those who think you're nuts to worry about peeling potatoes. Potato salad is just too well received, and too easy to make for so many people!

Our family potato salad involves unpeeled potatoes, cut into still largish, but bite-sized chunks, hard boiled eggs (apx 6 ea per 2 lbs. potatoes; I run them through a wire egg slicer twice--once, then rotated 90 degrees), fresh, uncooked thinly-sliced leeks (including the green bits), in mayo, seasoned with mustard (generally a dijon, but sometimes I'll add some dry english for added kick), salt and pepper and some good spanish pimenton. I make the day before so the leeks have a chance to mellow and blend in.

German Potato salad w/skin on is a must.
My Austrian Grandmother used to make Cabbage and Polenta this time of year. Just toss a head of cabbage in a slow cooker along with a few cans of tomatoes, whatever meat you have laying around, and some onion and let it simmer for a few hours. She would serve that over a nice garlic polenta.
Another must would be a soup since that is standard before most large German meals. Either a nice knoblauch soup (creamy garlic) or a simple Gulaschsuppe (German borscht) would go great with the menu you are planning, and both of them are very much fix it and forget about it.
For another interesting side dish try Karotten im Bier which my father is addicted to. Basically braised carrots in beer...the darker the beer the better the taste.
For desserts there are tons of tortes you can try, ranging from the easy to the intense. You can also do German Chocolate Cake or GC Brownies which are rich and most of it can be made the day before and then assembled the day of. If you can find a recipe for it Bee Sting cake is an AMAZING dessert that is nice and sweet and pairs very well with a nice dark beer.
Hope this helps!

I have to go with the German potato salad and braised red cabbage; I do the red cabbage in my slow cooker after I do the initial saute, and it works like a charm and is out of my way. You can also make latkes well ahead, freeze them on a baking sheet, then move into plastic bags....thaw and then crisp them back up on the baking sheet in a 350-degree oven for a few minutes before serving. With some apple butter and some sour cream....YUM!

No one wants to try the traditional German Cannibal Sandwiches I suggested to PeterSteinberg?

I like Antonia's suggestion of a platter. Trad. German would be an array of pickled items with cheeses and preserved meats. Also, definitely put out some braunsweiger (liver sausage) with dark rye bread and raw onions.

Some regional faves would be: pickled beets, dilly beans, little cornichons, etc. German sausages are nice, beyond brats. Summer sausage and landsjaeger are lovely accompaniments on a tray.

Germans also are big on sweets with their beer. So have fun with some chocolate items and linzer cookies.

Lots of apple-y desserts on the food52 site! Must make applesauce, too. Peel, seed, chop apples, maybe 8 cups, add 1 cinnamon stick, small piece of nutmeg end, 1/4 cup h2o, juice 1/2 lemon. Simmer low till mushy. So much better than store bought. Can be a side or dessert - serve warm w dollop of sour cream or yogurt.

Braised red cabbage - onion, apples, cabbage, red wine vinegar, red wine, brown sugar, S&P, and traditional herbs if you like them - caraway. A little of this on the plate adds great color and is a nice complement to all of the above suggestions.

You can also include bacon in this recipe. And it sits on the stove top without any muss or fuss.

Actually, I almost forgot . . . to do Oktoberfest right, you need several large platters of sturdy Bavarian style cheeses, some nice cold meats (maybe not necessary in this case, given the brats) and LOTS of radishes on the cheese platter, with some butter and salt. I'd also make some simple (undecorated) Lebkuchen for dessert, as they were everywhere at Oktoberfest when I was in Munich for the festivities there. The ginger cookies were perfect with everything else served. ;o)

german potato salad is a must. DonnyG is on the spot leave the skins on and move on to the dessert.

If you do decide to be OK with a little potato labor, this is what I love to do with them:

Cut up a bunch of pancetta or bacon into lardons. Cut red potatoes into a uniform rough dice. Brown the lardons in a pan, slowly rendering the fat. Use some of the fat to coat the potatoes, put them on a baking sheet, season with salt and pepper, and roast until there's a little bit of browning going on.

Get a large bowl and whisk together some good-quality mustard, vinegar, and salt and pepper. Stream in some olive oil to make a mustard vinaigrette.

Toss the roasted potatoes and the lardons in the dressing. Finish it with a lot of chopped parsley.

It is easy and delicious.

spatzle is a good idea, and it is not as labor intensive if you use a ziploc or pastry bag with a relatively small decorating tip. You just squeeze a bit of do and flick it off, kinda like churros. I would just do batches, and I have had it with a gravy like sauce but next time I will make it with a stout gravy.

Every German potato salad that I have ever had from a deli always has the skin on red potatoes. Don't worry and just go that route. With that menu you have to have potato salad! Sounds like fun!

For a side - how about spatzle? Yes a little labor intensive, but that's what makes it good. Would also recommend potato pancakes ( Kartoffelpuffer ), but then we're back to peeling potatoes. We sometimes make a cabbage and cheese sauce recipe we found at http://www.kitchenproject.com/german/recipes/Vegetables/CreamedCabbage/index.htm that we like.
I agree with jane though - thin skinned red potatoes with skin left on make a great potato salad. Good luck!

Sauerkraut is a must. Oven-baked store-bought sauerkraut would be easy, and perfect for an Oktoberfest party. Slice a few apples thinly into the bottoms of your largest roasting pans; add sauerkraut, sprinkle with a bit of dark brown sugar and some black peppercorns, stick in one medium bay leaf per two pounds of sauerkraut, pour over 1/2 cup of apple cider --preferably unpasteurized -- and toss lightly. Bake in a slow oven for a couple of hours, turning every half hour or so, and adding a glass or so of good white wine, if the bottom of the pan seems to be drying out or caramelizing too much. The cabbage will soften and caramelize with the other ingredients. It will be delicious, and the perfect compliment for your brats. You can make it in advance and serve at room temperature if necessary. Or just keep pans of it warm in your oven, crockpots, etc. Also, a bit more labor intensive (due to the chopping involved) would be cole slaw. Make it well in advance, and salt the cabbage for a couple of hours then rinse before adding the dressing, to tenderize it. Have fun and good luck!! ;o)

As to potato salad, don't peel--boil little reds w/skin on, pour over bottled Italian salad dressing while still warm. Stir roughly so that they smash up a bit and soak up the dressing. You'll get rave reviews!

Mini meatloaf sliders--really simpler than it sounds. Make your fave meatloaf recipe, cut into slices, then slices into quarters. Serve on the mini size potato rolls with a tray of whatever condiments you have on hand (BBQ sauce, pickles, assorted mustards, relish, chutney, etc). Everybody loves 'em!

I wouldn't give up on the potato idea if you use white potatoes with a thin skin. You could do one or more potato gratins with maybe gruyere or raclette style cheese. If you have access to a mandoline the slicing will go a lot faster.