I'll be arriving in Rome at 8 am and there is a tour starting at 10 am. Will we have enough time to get through customs, get to our hotel (Exedra at Piazza della Repubblica) to drop off bags, and make it to the Colosseum by 10?

Hi,

Based on our recent experience -Highly unlikely. We took a plane schedule to arrive at 8:04. We arrived at Roma TE at 11:20.

posssible, but unlikely, and you won't know exactly until you've tried it, is my opinion
It will depend on what's happening at baggage claim and customs at the airport,and how your transport goes from the airport to Rome--odds are against it. Are you arriving on a weekday?

That commitment would cause way too much stress for me

I was in Rome a few weeks ago and it took an hour for the bags to show up on the carrousel!

Customs takes a couple of minutes.

I think a 10:00 tour is unrealistic.

It's unrealistic. Further, why put yourself in an immediately stressful situation when you first arrive for what you hope will be a glorious Italian experienced.

Thanks for the advice. I will just book another tour later that day - certainly don't want to start off feeling rushed and stressed out!