Since all the certificates we use are for Category 1 - 5's, I was curious where you felt you either got the best deals or the best value for your certificate.
I have actually used several on the Courtyard Woburn Boston North. Nice hotel, just north of Boston - with a full bar, old style Courtyard restaurant and free coffee in the lobby. Also a nice indoor pool and fitness room. And it's only a Category 4.
In DC, I really like the Courtyard Washington Embassy Row. It is a category 5 in a fantastic location, with a very nice restaurant downstairs. The restaurant is not a Courtyard property, it just happens to be downstairs. Creative Food Without The 'Tude
Also, in DC, we have stayed a number of times at the Residence Inn Washington DC Downtown on Vermont. Try to get one of the rooms with a balcony facing Thomas Circle. Large rooms and nice sunsets. Breakfast is decent, but the location is awesome, being about a block or two from the White House - and it is a Category 5.
These are a few off the top of my head. Will add more when I have some time additional time to think about it.