I'm trying to figure why you want to use oil based paint on the furniture given that it's unlikely to have hard use like a door frame for example.
Have you ever tried buttermilk paint ? I must confess I can't easily relate to the colour names you used as alternatives - Williamsburg or Phillipsburg Blue. Are either of those similar to any of the colours in this colour chart ?
http://www.old-village.com/prod_williamsburg.html The name Williamsburg in the address is coincidental - I found that site ages ago whilst just looking for some buttermilk colours I could match over this side.
If you were to use that type of paint which is water based the whole issue would be very easy. Just flat off off the existing finish with wire wool and wipe over with meths to remove any grease traces, paint the whole lot of white with the cheapest emulsion you can find, as a base coat. and then paint the buttermilk colour on top. Buttermilk drys quite fast - when completely dry just seal the finish with dead flat water based varnish.
If you want a distressed look then use two colours - one on top of the other. When dry rub gently with a dry kitchen scouring pad on the places which would naturally be handled. This is the way in which repro New England candle boxes, for example, are painted to make them look 200 years old even though new.