I've made mashed potatoes the day before and they taste just fine reheated. They will dry out a bit, so add some milk or water when you warm them up again.

The make ahead recipe is really, really good. I've not used the crock pot, but have baked them the day before then take them out of the refer about an hour before the turkey comes out of the oven to let them warm up a bit, then put in the oven to heat up while the turkey rests, gravy gets made, etc.

I have made that recipe several times....I put it into a large glass casserole and put a piece of buttered foil on top and reheat in a 325 of 350 oven...whatever the temp you want.
I don't like the ultra slow crock pot thing....takes about 30 to 45 minutes in the oven....very good! Richer than "regular" mashed.
But I also make ordinary mashed potatoes an hour ahead and re-heat in the micro....right in the porcelain serving bowl!! ( and that's why I have stopped using my lovely white gold trimmed Haviland covered dish for mashed potatoes)

I have a similar recipe -- 5 pounds of potatoes, one stick of butter, 8 ounces of cream cheese, 8 ounce carton sour cream, salt and pepper to taste. If I use the little red potatoes, I don't even peel! Cook potatoes (peeled or not depending on the kind), until done, mash, add butter, cream cheese and sour cream and salt and pepper to taste. Mix all together and put into a buttered baking dish. Cover and Refrigerate (and can be made day ahead). Warm at least 45 minutes before serving at 350. They also are forgiving if someone is late they can be kept in the oven. With all the butter, cream cheese and sour cream, they don't seem to dry out. AND if you have any leftovers, they make great potato cakes OR potato soup! I figure the 5 pounds will feed 20 people. You can do whatever add ons you wish -- the garlic, rosemary, or make them "loaded" with cheese, bacon and green onions. I've made these for family dinners, weddings, elegant dinners. They're really good mashed potatoes.

I've made the make-ahead twice now, and they are really quite good. I didn't use my slow cooker for reheating though, I used my oven after the turkey was out and resting.

Thanks everyone for your replies, that's so helpful!! My oven is going to be busy warming cabbage rolls, perogies and a yam casserole, so that's why I thought of using a crockpot this time. I actually have 3 of them, lol. The other 2 are for s&s meatballs and stuffing/dressing. Ham will go in roaster oven - I've never glazed one before, btw!

Its 0100hr and now my tummy's growling after writing this :)

Only had time for a tin of sardines for supper tonight.

So is it the CC that makes it make-ahead? I thought I recognized the recipe in the OP as PW's, but hers is way richer. Sub half and half for the milk and triple the butter, for the same amount of potatoes. It's good.

I made the make-ahead potatoes that I always make today, for Sunday's Thanksgiving dinner.

It's the one from Best of Bridge, that uses cream cheese and sour cream. Potatoes are mashed, and mixed with the cheese and sour cream, and dotted with butter. They'll go in the oven while the turkey is resting.

Tomorrow I'm making the Turnip Puff

I used to make them years ago. They are very good but much denser than "fresh" mashed potatoes.

Love the do ahead potatoes. And if there are leftovers, you can freeze them for later meals.

Pretty sure the warm setting on new crock pots is equal to the old low settings.