One formula is to cater to the different lifestyles and desires of over-60 shoppers instead of lumping them into one category defined by age, says Gretchen Addi, a senior executive at Palo Alto, CA-based design firm Ideo. "Forget the numbers; the numbers don't mean anything," she says. "Age is not the indicator, so you might as well throw it out the window."

The number of people over 60 has tripled since 1950, and for the first time in history, that age group will equal those below 15 years old, says Pat Conroy, national managing principal of accounting firm Deloitte & Touche's consumer business practice. The $1.7 trillion that people over 50 spend annually is half of all spending in the country, he says.

Some specific things retailers can do at their stores to make shopping environments more friendly for senior citizens is place parking close to store entrances, have proper lighting, as well as a controlled noise level, a Deloitte survey has found. Other remedies that store owners might consider are larger print on signs and wider aisles, Conroy offers.

One retailer that is attempting to reach an older audience is Gap Inc. The San Francisco-based apparel giant in August launched Forth & Towne, a chain that sells clothing to women over 35. There are currently five Forth & Townes, one in West Nyack, NY, and four in the Chicago area, and Gap executives have said it could become one of the chain's largest brands.

"Targeting this age group was the next natural step in expanding our portfolio," says Alan Johnson, chief financial offer of the Gap chain. One thing that the chain focuses on is size, he says. The models used to design Forth & Towne clothing are size 10, compared to the industry standard of size eight, because 70% of women over 35 are size 12 and above.