I am planning a May wedding in Madrid and would like recommendations for somewhere to rent tuxedos for the
bridal party.

I would also be interested in the possibility of hiring a band to play at the wedding reception. Ideally, we would like a band that plays both contemporary dance music from Spain as well as classic rock-n-roll, Beatles, etc...

All recommendations are greatly appreciated. Thanks!

I don't have any suggestions but you could look for shops with tuxedos at yellow pages. http://www.paginas-amarillas.es
I have seen 55 shops about it