I will be traveling in Rome on a saturday and sunday and currently have saturday booked full of tours. Will I have any opportunity for shopping on Sunday or are all the shops closed? I know there is a market that is open til 1pm but any other suggestions?

What kind of shopping are you interested in. the souvenir shops will be open - don't thingk designers will be.

I've been mulling over your question and I think that if you can, perhaps switch some of your tours to Sunday, because Sunday isn't really a very good shopping day in Rome.

Larger department stores should be open on Sunday. I just looked at COIN website and the one on Via Cola di Rienzo is open from 10:30 to 20:00. Try Rinascente as well.

Unfortunately my tours for Saturday are of the Vatican and other religious sites so Sunday is not an option. I am looking to get all types of shopping in. I hear the Porta Portese is a large and fun market on Sunday. Any feedback?

Porta Portesa has changed over the years. You have to do a little more searching now - not the same type of merchandise as 5 years ago... but it's certainly an experience. See this post for some pictures: http://tinyurl.com/porta-portese

Much of what you'll see there is also sold at bancarelle throughout the city: http://tinyurl.com/bancarelle

You'll find larger stores open on the Cola di Rienzo, Via Dei Corso, or Via Nazionale. Many of the smaller or specialty shops will be closed on Sundays. Many are open till 20:00 on Saturday evening, so that might also be an option for you.