generally, mashed potatoes are the norm for sunday dinner.
but when you're in a hurry, nothing's faster than a baked potato (assuming you think of it ahead of time). i like to do baked potatoes because you just wash 'em, wrap 'em, and stick 'em in the oven and that's it. so if you want to come home from church and eat right away, go for baked. if you've got some time, mashed are good too. whatever floats your boat. you can see how to make mashed in this post, if you don't already know.
so let's get started. you'll need some potatoes and foil. i like big idaho ones because i looove baked potatoes and a small one just won't cut it. so get your potato, and scrub it under warm water. you want these babies cooking clean!
then cut a few pieces of foil, wrap them up, and stick 'em in the oven for at least 3 hours at 250*. if you're in a hurry, microwave them for 5 minutes and then cook them at 375* for 45 minutes to an hour. if you've got time (like on sunday), don't worry about the microwave. the oven will do just fine.
once dinner is ready, cut these babies in half, scoop out the potatoey goodness, add some butter, salt and pepper, and lots and lots of gravy. you won't regret it.