757 is ultimate acft for short and midhaul charters. it have good capacity being all-economy configured, it have enough range (for european companies) to operate f.e. any leasure destination in Europe, North Africa, Canarian, Middle East.
also 753 is known to have cheapest seat-per-mile costs of any narrowbody acft.
it have capacity comparable with 767 but maintanance is much less expensive.