The standard for tyre width on a road bike for several years has been a 23mm tyre.
Over the last few years there has been a trend toward 25mm. Not just by recreational cyclists either. Orica Greenedge, FDJ, BMC Racing, Omega Pharma & Sky are just a few of the teams running the wider rubber on the UCI tour.
Going to 25mm allows you run a lower tyre pressure (perhaps 15-20 psi less) without the issue of pinch flats. Which makes for a more comfortable, compliant and this safer ride. You have that bit more rubber on the road, so your traction is also improved. The bike will have more grip and is harder to unsettle, as well as being more comfortable.
The interesting thing though this doesn't though come at the sacrifice of speed (hence the pro teams adopting it) - in fact the 25mm option is faster under most conditions. The physics behind this isn't simple. But in short, the rolling resistance (i.e. friction) created by tyres isn't so much caused by the contact area of the tyre, rather how much the tyre distorts from it's standard shape when in contact with the ground. And 25mm tyres are much better than 23mm. Aerodynamically 23mm tyres have an advantage, but the rolling resistance benefits outstrip the aerodynamic drawbacks.
The road surface also has an impact. If the surface is billiard table smooth, 23mm tyres might be the better bet, but on bumpy, coarse chip roads, 25mm tyres are the clear winner.
So throw tradition out the window, and strap on some 25mm rubber. Most bikes will take 25mm no dramas, and you're unlikely to need to change rims. You'll be safer, more comfortable, and quite possibly faster. And if it's good enough for Cadel Evans, Richie Porte, Chris Froome, Simon Gerrans, Matt Goss, Luke Durbridge, Mark Cavendish & Tony Martin, my guess is you'll cope fine.