A nice day or weekend trip for you would be to go down to the "Bluff Country" of southeastern MN. There are two very nice bike trails (Root River Trail and Harmony/Preson Trail) which link a variety of picturesque little towns.
Some good roadfood-type joints in these towns include:
- Wheeler's (a combination roller-rink/burger joint in Harmony)
- Das Wurst Haus (a sausage and brat place in Lanesboro--probably the most touristy of these little towns, but still very nice)
- Victory Cafe in Preston (the most roadfoody of all, it's your standard midwest small-town main street place, with those real mashed potatoes you were looking for, as well as some great pie!).
Also, I lived in Minneapolis for two years and Saint Paul for seven years. I'm partial to Saint Paul--they have everything Minneapolis has, usually for less money, and usually with more parking. The best pizza in the Twin Cities is at Red's Savoy Inn on Seventh Street in Saint Paul. It's a dive but the pizza is fantastic. (Make sure yours has Italian sausage on it.) It can be very crowded, it can be smoky, and parking can be a challenge, but it's very worth it. Here are some customer reviews: http://twincities.citysearch.com/review/5516886/?cslink=cs_profile_tabs_user_review