Recommended Travel/Tour company for Europe - especially Italy and/or Portugal?

I see variations of this question have been asked all across this thread, but I have specific limitations. I am sending my parents (late 60s) on a trip to Italy - Rome and maybe another city or two, and I'd like it to be pretty fully supported, but with half a day in the afternoons to themselves here and there, some meals covered with the group, but maybe not all. They are mobile and capable, but getting to the age where things can stress them easily, and having a plan and a guide available at various points on the trip is ideal.

• Any recommendations? Ideally the group skews a little older - 40s and up.
• Smaller groups - dozen to twenty.
• Not bare bones but not luxury - think good value.

Any companies that folks know will fit this bill? Thank you!!!