Swanky's at Poplar and Kirby is not bad for burritos and tacos. One of the "new wave" burrito places that have finally invaded Memphis.
Further north on Germantown Parkway is the best mexican in town at Tortugas Deli Mexicana. It's where Germantown Parkway crosses the Wolf River. May be out of your way but it's on the northern Germantown border.
You didn't ask about Asian, but Mosa is also at Poplar and Kirby...hard to find in the shopping center mess on the north west corner, but worth it for a mix of Thai and Chinese.
Pizza--only recommendation I can give is Ciao Bella further into Memphis near Poplar and Mendenhall--right next to a Kroger behind the Paradiso movie theater.
Have fun and hit some good BBQ in Midtown at Central or BBQ Shop to round out the Memphis experience.