James Somers thinks you should switch to the Websters 1913 dictionary, and he cites John McPhee's composition method of looking up synonyms for problematic words as the key to his peerless prose style. Somers makes a great case for the romance of historical dictionaries, but for my money (literally -- I spent a fortune on this one), the hands-down best reference for synonyms and historical language reference is the Historical Thesaurus of the Oxford English Dictionary, whose magnificence cannot be overstated.
It makes sense: there was, and is, something remarkable about his 1828 dictionary, and the editions that followed in its line (the New and Revised 1847, the Unabridged 1864, the International 1890 and 1900, the New International 1909, the 1913, etc.). You can see why it became cliché to start a speech with “Webster’s defines X as…”: with his dictionary the definition that followed was actually likely to lend gravitas to your remarks, to sound so good, in fact, that it’d beat anything you could come up with on your own.
Take a simple word, like “flash.” In all the dictionaries I’ve ever known, I would have never looked up that word. I’d've had no reason to — I already knew what it meant. But go look up “flash” in Webster’s (the edition I’m using is the 1913). The first thing you’ll notice is that the example sentences don’t sound like they came out of a DMV training manual (“the lights started flashing”) — they come from Milton and Shakespeare and Tennyson (“A thought flashed through me, which I clothed in act”).
You’ll find a sense of the word that is somehow more evocative than any you’ve seen. “2. To convey as by a flash… as, to flash a message along the wires; to flash conviction on the mind.” In the juxtaposition of those two examples — a message transmitted by wires; a feeling that comes suddenly to mind — is a beautiful analogy, worth dwelling on, and savoring. Listen to that phrase: “to flash conviction on the mind.” This is in a dictionary, for God’s sake.