Whilst it’s fun to ride alone, at times it’s also good to have some company. There are several sportive type events (mainly in Europe) aimed at vintage / retro bikes. Here’s the ones that I’ve found:

Pendle Witches, Lancashire April 12th: http://www.pendlewitchesvintagevelo.co.uk/

Beret Baguette Ride, Paris, May: http://www.beret-baguette.com/

Anjou Velo Vintage, Saumur June 23 /24: http://www.anjou-velo-vintage.com/

Retroronde, Flanders, Belgium, July 1st: http://www.crvv.be/en/museum/activities/retroronde

La Patramonie, Favieres en Brie, France, September: http://www.lapatrimoine.fr/

Eroica, Italy, Early October: http://www.eroica-ciclismo.it/english/home.asp

Tweed Run, London, November: http://tweedrun.com/