Sneakers would be best and Cross Trainers are best for walking, running and working out. If you go to a modell's or foot locker etc. and ask them which are the cross trainers they will show you, you can also ask for anythign else that's good for walking.
Basically Cross Trainers sort of go up in the front (if you look at the sneaker, paying attention to the sole, the front end goes up off the ground when the sneaker is just sitting there on the shelf, many sneakers for like just wearing to school or work are totally level/flat to the floor).
Once you learn the difference in the sneakers you can go to an Outlet store like JC Penney Outlet or Marshall's or even maybe a Kohl's and get a decent pair for a better price than a sneaker store.
Gook Luck!!