Hi
I have family there. They walk to the stores almost daily. It is not a bad walk at all... depending on your heat tolerance, you might not be doing it all summer, though. Distance would depend on where exactly within Sun Village you were looking. There is a residents-only gate in the back for both walkers and drivers which is a big help.
There are a LOT of stores and restaurants in that area (Bell/Grand/Litchfield) but to walk to the closer ones takes my relatives about 10 min.
The area does get busy at rush hour. Pretty much anywhere along Bell or Grand is busy during then.
Oh, and as far as the community goes-- they have so much to offer. It seems like there is a club for everything under the sun. They also have happy hour, dinner dances, etc as well as a beauty shop, restaurant, golf course, tennis courts, shuffleboard, exercise room, woodworking room... the list goes on and on. The pool offers water aerobics and volleyball. I believe there are also day trips.