Basic: One with 13 unique valid English words, using 4 punctuation marks:
See Al sass lass Ella’s sea seal lease sales; ales, leas, leases all sell less. (Letters: AELS)
Improved: One with 17 unique valid English words, using just 1 punctuation mark (letters courtesy of @bobble):
A tea set asset at east sea teases estates; See attests estate ass seats tease test seat assets. (Letters: AEST)