Hi Roxanne, perhaps I can just give an example of what we offer as a professional wedding band (Trio).
From our experience, guests are always thrilled when they learn there is a live band providing the entertainment for either the ceremony or reception. We offer live music for both of these (and also Canapes).
For ceremony, and early in the reception, we present mellow acoustic style music, which is typically what you would want prior to the main meal and bridal waltz. Later, (post bridal waltz) we pump up the volume and tempo converting ourselves into a sequenced dance band, playing a wide range of popular hits that will appeal to the wide range of age groups you will have at a typical wedding. Most bands, including ourselves, should have a complete song list on their web site.
You do not need a separate DJ for your reception, as we also look after all of the music between the live sets, as well as for all the nights other events such as entrance, waltz, cake, games etc. In fact we discuss and also plan this as part of our pre-wedding planning we go though with each client. This give the opportunity to include some other music which may not be in the live sets. Because we do both, we can make sure there is no overlap of songs, and see the smooth transition between the live sets and pre-recorded (DJ) music.
Of course, best advice is to first discuss all of this with any band before booking, to be absolutely sure they will cover the whole night's entertainment needs.
I hope this helps.
Best regards, Pete