We have 2 full days to spend in Rome in early September. I've arranged for a guide for our second day to see the Vatican Museum. That afternoon we will see the Borghese Gallery in the 2 hours the museum allots for a visit.
Our first day we arrive in the airport at 715 am and are staying near the Pantheon. I've mapped out a walking route, using Rick Steve's Rome book, that will start at the Pantheon, and tour 2 or 3 small churches on the way to Piazza Navona. Then walk to Piazza Venezia/Victor Emmanuel Monument/Piazza Campodoglio. How long does it take, generally, to tour this beautiful Piazza?
In the afternoon, we'd like to next walk down Via dei Fori Imperiale to the Colusseum, and see the Forum, Palatine Hill and the Colosseum on a combined pass. My second question is, I know I need to purchase a combined pass ahead of time, but I'm confused as to whether "skip the line" is a marketing ploy for a guided tour, or if it's the fastest way to get in. Obviously buying a ticket ahead of time means you won't wait in line for admission. Is a guided tour necessary and worth it? I am not averse to thoroughly researching a site and touring on our own. (Following Rick Steve's guide for Pompeii along with information from the official site, we thoroughly enjoyed the ruins in 4 hours).
I'd appreciate advice on my two questions. Thank you.