My take along is usually redwork (doesn't necessarily have to be red, either. I just started one of big game animals that I am doing in forest green thread). Blocks, needles, threader, small scissor, hoop and embroidery floss all fit into a quart or gallon sized ziplock bag.
I love to keep the bags that curtains come in as they are much sturdier than ziplock bags and often better sized for small hand projects.