I stayed at the Residence Inn Pentagon City for 3 nights while attending a meeting and was very pleased.
Adam, at the front desk when we checked in, was amazing. He changed rooms, split charges between credit cards, got a message to someone who arrived late. He really helped make our trip successful.
I was in a 2 bedroom suite with friends - lots of room. The view from the 17th floor was wonderful - the Capitol, Washington Monument. It was also very quiet and the queen beds and linens were top quality and very comfortable.
Breakfast was good - always nicely cooked scrambled eggs with different choices of meat or potatoes, cereal, waffles, fruit, various breads and pastries.
The walk to the Metro was easy, but the shuttle was also available to drive you there or pick you up if needed. Also a free shuttle from National Airport.
The only disappointment, and why it got a 4, was the quality of the mattress on the pull-out sofa. It was terrible - all you could feel were springs. We were a party of 3 and one person did manage to sleep there by putting the couch cushions on top of the mattress and then the sheet. I would definitely not plan on using the sofa bed for an adult, and even a small child would need several blankets or the cushions to be able to sleep on it. If you only need the regular beds, all was excellent.