I have been in Arequipa almost a year now and it is a fantastic city, I felt at home straight away.
I volunteered with Traveller Not Tourist, a great low cost organisation who help an orphanage and kindergarten in Arequipa. I volunteered in the kindergarten and loved it, the children are amazing! Traveller Not Tourist is also a tour agency who book tours around Peru with 50% of the money going to the projects and they´re trustworthy!
I also lived at Ceica Peru Spanish School. A fantastic school with great teachers and very flexible. The lessons are in a lovely garden so it´s a nice atmosphere. The teachers completely adapt their lessons to you and your level of Spanish which means your Spanish progresses really quickly. The style is so different to at home, but so much better!
Colca Canyon is close by, and is beautiful. I would definitely recommend the 3 day trek. It is also so easy to get the beach in the Summer months. There are great restaurants in Arequipa, my favourites being Hatunpa, Arthur and Capriccio.
Arequipa is a beautiful, friendly city and I would definitely recommend a visit there and to improve your Spanish at Ceica. If you have a bit extra time do volunteer with Traveller Not Tourist - it´s a lifechanging experience!