Personally, I would get involved with a single or double CPA office that needs some help. Now is the time to start looking as they are going to be hiring for help in the next couple of months to prep for tax season!
Getting involved with big tax firms sometimes hinders you from getting that one on one learning.
I might be a little biased as I've always found it more enjoyable to work for smaller CPA offices with one or two on staff that are looking to bring someone on and help them achieve CPA status.
Also, keep in mind that during tax season you'll say goodbye to your family from about mid January to April 15! 15+ hour days 7 days a week. It's rough! But, pays well! REALLY well!