What I loved most about the Donovan was their amazing team! After that, you should know that the rooms have great design--for comfort, cool factor and functionality (which is important for work travelers). I'm a big fan of their complimentary happy hour in the lobby and the pool bar area was a perfect place to shake off the day. I also ate in their restaurant Zenten and would give their food and staff high marks as well.
I travel frequently for work and it's always a treat to stay in a hotel that feels like it's in a neighborhood--good for those who like to walk and run outside for a change. Thomas Circle is abuzz with neighbors and lots of dog walkers.
If you're heading to DC for the tourist spots, you'll either have a bit of a walk or need a cab. I enjoyed being a bit off the main drag since you walk so much that a cab is a nice break.
PS: The funky leopard fuzzy bathrobes were a treat!