The value of a president

Without going too much into my personal politics, I’m noticing a lot of people saying Sanders won’t be able to get anything done. I’m curious how much this really matters? Something I remember people saying about Obama was that it didn’t matter if congress wouldn’t work with him because the real value of the president is their cabinet picks and policy.
Simply, how important is it for a president to personally accomplish things in office, and with the vastly expanded powers of the office, how much does it matter anymore how cooperative congress is?

First post, be gentle!

Well, Obama couldn’t even get a vote on his appointment of Merrick Garland to the Supreme Court because Senate Republicans simply refused to schedule hearings.