Our favorite Thai restaurant in the area is Little Spice in Hanover (on the other side of Rte 100 from the Arundal Mills Mall), a family-run place with great service and great food. We like all of the noodle dishes, especially their version of drunken noodles. The eggplant with basil is terrific, as are all of their green and yellow curries. Spicy, flavorful, but not too spicy.
There's a lot of fuss about the new pizza places in the area, but our dependable standby remains Pasta Blitz on Rte 108 in Columbia, which serves a true New York Style pizza. Lightly-sauced (and very tasty) with a thin but chewy crust. We get it for take-out.
And we're fans of the interesting vegetarian dishes at Mango Grove in Columbia. Try any version of oothappam, their rice and lentil pancake entree, to get a sense of their unique cooking.