If your store cards/credit cards have no fees, I would just keep them open. I have several store cards that just sit in a drawer. If they have fees, I am usually in the camp of cancelling and signing up for something better/getting a sign-up bonus. Sometimes Kohls and Old Navy have benefits for their card holders, which may come in handy.
I am in the camp of using credit cards to travel hack for free trips and travel. Many of the financial bloggers travel hack and use credit cards for free travel. So long as you pay off the balance and it does not increase your normal spending levels/pattern, I think it is a great tool for saving money. If you don't pay off the balance or it increases spending, then you negate any benefits though. We are taking our first trip this summer using this method. 8 nights at a resort and $800 in flights completely free for 2 people.
Even when you don't spend much in a given year, it is very easy to rack up points using sign-up bonus and spend categories. If married, each person can sign up for their own card for the bonus. Meeting minimum spend can be tricky, but we try to sign up for a new one before our car insurance is due or other big purchases, and alternate between who is getting the new card. Many cards provide lots of benefits, but I would recommend reading some of the travel blogs and forums and you can get a sense of some of the benefits. If you don't travel, there are products that offer 2.5% on all purchases, or 2-3% at categories (such as grocery, for no annual fee).
Some of my favorite sites are Flyertalk, Mommy Points, Travel Codex, Richmond Savers, View from the Wing, Frugal Travel Guy, The Points Guy and Doctor of Credit. I would recommend checking these out.