Isocrates’s Panegyricus advocates a Hellenic confederation under Athenian leadership for the purpose of opposition to the Persians. I think the ideas in this speech are comprehensible to readers of history or political science. Having accessible ideas makes it easier for the intermediate student to focus on the Greek language, which is more of a challenge.
It’s a long speech, but solving the puzzles in the long sentences for this intermediate student is rewarding.