Black Diamond Guiding Light.
5 pounds, 6 ounces. Holds 4 or 5 boys. Weatherproof, bugproof.
I've used lighter weight shelters, tarps etc. in the past and haven't been happy with them for scout use.
Having a haven from mosquitoes is key. Also, we often camp high, in places that are exposed to harsh weather. At a little over 1 pound per boy, these tents provide excellent shelter for the weight.