There are two plans the 401k and 403b. Since you have made a choice to be 401k Alright.
But this are the few benefit you will receive from IRA

• It can help you save from expenses.
• There several mainstream investment which includes, cash in savings accounts,certificates of deposit, but there other riskier ones which is what you likely want to go into. They include; mutual funds and ETFs. These investment depends soley on your goal and your ability to take risk in your savings.
  So your goals should guide your choice.