It's not a long walk, but there are lots of streets to cross because of the way DC is laid out. I found it a PITA when I did it with a rollerbag, but that was a blustery day in November.
Personally, I'd say you may as well take a cab if you are staying at the Ritz. Especially if it is the slightest bit hot, cold, rainy, windy, you are travelling during rush hour, etc. If you feel like a walk on a nice day, then go for it.
If you mean the Ritz at 22nd between L & M, easiest is to take a cab. Typical fare is $13-15 + tip & presuming you aren't in traffic, it's a 10-min. ride. For $15 more you can book a Red Top Sedan and skip the cab line (which is typically short).