Athens lodging covers the full range, from one to five stars, but it can all be a bit drab for the price, especially in the midrange, where there's a relative shortage of options – or at least a shortage of inspiring options. For this reason, you really must plan a couple of months ahead to be sure of your first choice. For July and August, ideally aim for four months ahead.
The Panhellenic Camping Association (www.greececamping.gr) maintains a list of campgrounds rated by the EOT (Greek Tourism Organisation) and www.travelling.gr list sites in the Attica region. The closest to the city is Athens Camping, 7km west of the centre on the road to Corinth, but it is not particularly notable. Better camping options are at Shinias and Cape Sounion.