Sorry IB - BA have never had 737-100's. The 200's were retired years ago. What's left are the 400's & 500's which are in fairly good shape from a Cabin point. yes there is the odd seat that will automatically recline but that should not be taken as an excuse that all 737 aircraft are in a bad way. BA take pride in looking after the interiors and defects are dealt with quickly.
As for the 320's the ones I have flown on have always been in pristine condition. The Old BCal ones are due to be retired soon I believe.