What are some tasty recipes for dairy-free mashed potatoes?

Substitute chicken broth for cream/milk and use soy butter.

although I'm not a fan of it, Mayonaisse or miracle whip.  if its lactose issues only, I would just add lact-aid to some cream to it. or you can use plain active culture yogurt because that has very little lactose.

Lactose intolerance is quite common in Asians and other non-whites, milk protein allergy not so much in grown ups. In South East Asia we used to omit the milk products in the recipes, and not knowing how using milk products would taste I'm quite OK with omitting milk since I'm one of the lactose intolerant persons.

I add olive oil...Tasty

The goal in mashed potatoes is to get them soft, light and full of flavor. While butter is close to a requirement you CAN do without it. First of all cook your potatoes differently. Bake them in a 400 degree oven for well over an hour until a knife goes in easily all the way through. Let them cool enough to handle and break the baked potatoes open and gently scoop out the insides. If you have it, run them through a potato ricer. If not, mash them VERY gently with a fork. Season with salt and pepper and add olive oil while carefully folding or stirring the potatoes to incorporate without smushing them so they are heavy.  You should have light, fluffy, tasty vegan mashed potatoes.

peel the potatoes and cut them up.  When the potatoes can be easily pierced with a fork, they are ready.  The key is to reserve the water that the potatoes were boiled in when you strain them in a second bowl.  Dry mash the potatoes thoroughly, then add some of the boiled water back in.  (for 5 to 6 medium sized white potatoes I use about a cup of the original water).  Then mash in your favorite dairy free margarine and salt to taste!  Enjoy.