Do not limit income while collecting social security. Currently, income is unlimited if you have reached FULL retirement age. Make this the case for any retirement age with no penalties.
This will allow people to continue working as much as they need/want to save money for their future needs reducing dependance on family members, the government, and/or other agencies.
This idea costs the government nothing. In fact, the government will continue to make money from income tax.
A win-win.