If I want to get a feel for a systems overall reach and capability while still listening to real music I find a good pressing of the eponymous Rickie Lee Jones essential. The parts where Mr. Scott and the horn section are stretching out are brilliant from a evaluation perspective. Musics pretty hot too. Any of the 'audiophile classics' that you like, especially the well done direct-to-disc ones are perfect tools to help review a system.
New speakers are a huge event for us music lovers and can have the most obvious and immediate effect on what you hear. Changes like cartridges and amps and power cables can sometimes make improvements that take a while to sink in. If the speakers are a genuine improvement much of that jumps right at you (in general, no quibbles please).
My new speakers were two weeks old yesterday and they are begging me for a coffee break. Get back to work I respond!