The basic theory of wine pairing is to match the intensity of flavour of a wine with the flavour of the food. If you are dealing with subtle flavours then you want a delicate flavoured wine. Delicate and sophisticated wines tend to be expensive so, save your money. I'm not saying buy the cheapest wine you can find, but the heavy flavours of a barbecue are well matched by less expensive wines.
When you need a bottle of wine for a barbecue but you have no idea what to aim for, grab a bottle of something full flavoured such as Zinfandel, Cabernet, Shiraz or Merlot for a red or a Chardonnay or something similar for a white. These wines work well for most occasions and are great choices to take to a barbecue when you don't know exactly what is on the menu. Why not take a few speciality beers as well!