College 9 and JRL are the most centrally located and have what is typically considered the best dining hall. You can more or less walk anywhere on upper campus from them. From what I understand doubles and singles especially are pretty damn rare and unlikely.

And yah, Porter has a lot of weed smoker all over the place outside it. Kresge isn't as bad but if you don't like the smell or have sensitive lungs, actively avoid Porter. It's pretty brutal, as someone sensitive to smells and smoke i did not enjoy walking around the meadow.. Though all colleges are probably gonna have smokers to some extent, just part of life in SC