B737-800 was ideal choice in terms of size and seat cost pm 2 years ago, that is why we started buying them,indeed the TUI fleet now consists entirely of 737ng apart from by 757s on the narrow body side.
757-300 has inferior performance to 200, difficult to turnaround quickly with single door boarding etc etc, Condor are contemplating scrapping theirs if boeing wont take them back and there is one parked here permanently on the ramp as a gate guard.
757 300 could only be used to replace 767 200 for by and a310 for hapag lloyd, (remember TUI airlines are being aligned wherever possible), and I just cant see TUI buying an a-c that they wont be able to sell on and that cannot operate long haul if required.
By the way looks llike a right dog as well...they should have made a shorter 75 instead.
rgds FH.