They don't have many 757-300's, so you won't find those on many routes. They have 4 of them now, if not 4, 5 but not more than 5. They originally ordered 15 units but they recently converted 6 of those to 737-800's among the remaining 11 they still had on order at Boeing. Their 757-300 fleet won't grow much, it'll grow up to 10 units at the very most. Yes, they are based in EWR
and are assigned to Florida destinations, because EWR
-Florida is the only sector in Continental's system where there is a market for the aircraft. There a lot of leasure travellers living in the area of NY City flying down to Florida for Thanksgiving, X-Mas holidays, February/March...hi-peak seasons in the year. FLL
are two good examples for leasure destinations.
I'm not sure there are any 757-300's based in IAH
eventhough it's Continental's largest hub.