For those of you looking to branch out beyond whites, roses, and heavy reds (for BBQ), here’s a good list: Chilled Red Wines to Drink All Summer – Bon Appétit.
Beaujolais is the obvious choice for Gamay, but lots of new world producers make wine with that grape. For Carignan, you may have to look around: if you can find a place that stocks a good selection of French wine, look in the Midi section. Also check out the Spanish wine section. The challenge there is it can sometimes (often times?) be blended with heavier reds. Ask the staff for help if you want something lighter. As for Zweigelt, the challenge there is finding it at all. If you can, get some.
If you want to know more about carignan, check out this from Winefolly.com: