Headed to DC this summer for a four day stay. Planned on staying in Alexandria and use the King Street Metro Station. Is this a good choice and can someone recommend a hotel? Would there be a better location or area to stay in while there?

Good location.  I live and work near the King St metro station.  Feel free to PM me with any questions.

I stayed at the Hotel Monaco on King Street.  Got a great discount online.  It's the site of the hotel where Col. Elmer Ellsworth was shot by the innkeeper for taking down the Confederate flag.  The Sons of Confederate Veterans put up a plaque honoring the innkeeper (but it doesn't mention Ellsworth).

Eat at Gadsby Tavern.  Washington ate there.

Visit the Carlisle House.  Gen. Edward Braddock planned his campaign to capture Fort Duquense (modern day Pittsburg) from there.  He ignored the advice of Benjamin Franklin and brushed Ben off with the comment that while the N-D-Ns could fight the militia, upon the King's soldiers they could make no impression.  Braddock was killed and suffered around 60% casualties.  

There's an apothecary there that purportedly Stuart met Lee and told him to make haste to Harper's Ferry with a detachment of marines.  

Patent Office Museum is within walking distance to King Street Station.

BTW, last time I went I stayed at the Travel Lodge (got a great rate for a week long rental).  Two blocks away is a Trader Joe's.  Plenty of parking there at Travel Lodge (good consideration if you have a car).