Travelling to Spain at the end of April

I'm going to be travelling to Spain at the end of April for a vacation by myself. I'll be arriving in Barcelona before making my way down the coast to Valencia, Granada, Sevilla and back up to Madrid.

If anybody has any recommendations on where to stay, what to see it would be greatly appreciated. Also if there are any expat events going on in these cities that I could attend please let me know - I'll be travelling on my own for a portion of the trip.