We found the two hours we were at the Borghese Gallery adequate for seeing all the rooms with time to focus on the pieces most interesting to us. We don't know how much time you plan to devote to each piece nor how many are on your list but two hours is adequate for all but the most in-depth visits. It isn't a huge gallery albeit rich in treasures. Here's where we wrote about our visit, accompanied by Paolo from Trieste: http://www.thetravelzine.com/rome0301_1.htm

Regards, Don and Linda