I did a Nile cruise in 1986 from Aswan to Luxor - it was not, however, on your particular riverboat - the one I sailed has probably gone on to it's final resting place (at least one can only hope). Don't get me wrong. We had a ball - it was just that the boat itself was so old, it could have been in a Poirot TV mystery!
There really is no "better side" as you will be spending the bulk of the time on the observation deck anyway (at least I did) when you are not pulled over to visit some of the antiquities. When I went, there were no "additional shore excursions" so I can't help you there.
Couple of things to consider, however are: 1) allow enough time to visit Abu Simbel before you depart as well as enough time to visit Aswan; 2) IF your cruise ends in Luxor, stay there for a few days to visit the Valley of the Kings, Valley of the Queens and of course, Luxor and the Temple of Karnac. I stayed at a Sofitel resort on Crocodile Island.
P.S. The local beer (non import) is delicious and the horses that pull the carriages along the corniche love it too!