I am interested in traveling to Arequipa, Peru this or next month and had a couple of questions.
I’ve been to Arequipa before, speak fluent spanish and familiar with Peru so is it recommended to go on a Tour of Arequipa or would it be ok to visit the attractions on my own schedule?
For those of you who have gone on a tour and where satisfied, please recommend the tour company and supply the website as well to check them out.
I know there is the Sta. Catalina, Colca Canyon but what else is there to see?
Also, is March-April a good time to visit Arequipa or is there a more adequate month?
Thanks in advance for the help and major points to the person who can answer all my questons! 
Hi! We visited Arequipa and loved it. We spent one day pounding the pavement on our own within the city to see the sights within walking distance. It was easy and convenient. Sta Catalina was amazing. We also went to the museum where they have the mummies retrieved from the mountaintops (grim-they were child sacrifices-but the exhibits were really interesting and fascinating). I’d recommend a good guidebook to plan that part of your trip, like Lonely Planet. Wikipedia has good info on sightseeing too: http://wikitravel.org/en/Arequipa#See
We did do one of the open-top bus tours that we bought right on the main square. I can’t remember the name, but all the tours went to the same places. It was a 4-hour tour and we saw lots of interesting stuff that we wouldn’t have seen on our own. It goes on a tour of the outskirts of the city to places tough to get to on your own. The only goofy stop was the Alpaca factory store (merch, anyone?) but even my jaded self found a great deal on a sweater! It wasn’t too expensive either, maybe less than $20 per person? The guides were good. The places with extra admission were inexpensive and worth it too.
As for weather, I think it’s pretty much always the same. It was mid-upper 70’s (F) and bright, bright, bright sun. Nights were a little chilly but no jacket required, just some sleeves and long pants.
Other than that, you know the rules about altitude if you’ve been to Peru-take it easy and drink lots of water and wear sunscreen!
We didn’t go to Colca Canyon, because we weren’t planning to go to Arequipa in the first place (another part of our trip got canceled last minute so we picked the first place outta Cusco with cheap airfare!) but everyone we met loved it. You should plan two days for that one, from everything I heard.
Enjoy your visit.