Kendra
Your beetle is one of the longhorned beetles, family Cerambycidae, and actually one in the subfamily Prioninae. The photo is not clear enough to ID further.
As you noted these are large beetles!! They are attracted to lights at night so that is probably why you found it on the porch. The larvae feed on rotting wood that is sitting on the soil.
The 'sack' you see is probably the ovipositor of the female...where the eggs come out.
The jaws or pincers on the female are smaller than on the males of this group and the antenna are also smaller on the females than the males.
The beetle order (coleoptera) of insects have two sets of wings like most insects (except flies)...however the top set of wings are hard and protect the body while the under set of wings is what helps them to fly. Most beetles are not great fliers because of this...but they get around OK.
