I am planning a family trip to Italy this summer and we are taking our four teenagers (17, 16, 14,12) Should we stay away from group tours and do our own thing?

thanks!

Hmmm!
Did you mean a tour group for the entire trip or just guided tours in Rome etc.?

I cannot imagine a group tour with that age of kids

With kids that age, you may want to do fewer cities and try to rent apartments rather than stay in hotels. Teens can spread out, hang out, and eat at least some meals in.

If you go to Tuscany, you might want to rent in the country and see the towns during the day because many villas have pools.

The big caution I would have with teens is making sure they know how expensive it is to use their phones etc. I would make a wifi only rule for the duration or you may have a thousand dollars in Tweet bills when you get home.

eurocheapo.com
sleepinitaly.com
italyby.com
travelforkids.com Italy

Booking family style and training on group rates seat61.com/italy would save you boatloads of money.
My wife and I do this a lot rarely with our son.
3-4 days EACH in Venice Florence Roma works great for newbies
ricksteves.com nice tours affordabletours.com avoid gate 1
BBB F rated.When I newbie many moons ago did tours prefer the freedom flexiblity of self guiding and training around these days. aa.com farecompare.com cheap air in... MXP(Milan)
usually very cheapest for us. ostia-antica.org neat for kids
1 euro on the metro from central Roma.May June Sept Oct way
better than hot chock a block summer.

Happy Planning!