To start...Is this your first trip to Italy and/or Greece? Is that why you are attempting to do so much in such a short period of time?

As stated by the others, every time you move locations, you lose between 1/2 to a full day. It is simply a matter of checking out of a hotel, getting to the transportation place, taking the transportation, leaving the next transportation place to new hotel, checking into the next hotel. No matter what, these things do not change.

Now, if this is a first trip, but you figure you will return, then maybe it makes sense, as sort of a "taste" of the various locations. But, you have 5 location moves, excluding the long-haul flights. You are probably eliminating 3-4 days of your trip due to this.

Okay so I decided on the itinerary below. Phew! trip planning is exhausting (but loads of fun). What do you think?

Tuesday Depart Houston for Milan
Wednesday Train from Milan to Florence, night in Florence
Thursday night in Florence
Friday Train from Florence to Rome, night in Rome
Saturday night in Rome
Sunday night in Rome
Monday night in Rome
Tuesday Train from Rome to Sorrento, night in Sorrento
Wednesday night in Sorrento
Thursday Day trip to Pompei & Vesuvius, night in Sorrento
Friday Fly from Naples to Athens, night in Athens
Saturday day trip to Delphi, night in Athens
Sunday night in Athens
Monday Depart Athens for Paris, night in Paris
Tuesday Depart Paris for Houston
Tuesday Arrive Houston

so you've got this:

1 night milan
2 nights florence
4 nights rome
3 nights sorrento
3 nights Athens
1 night paris

6 places in 14 nights - too many IMHO.

you are flying into Milan, and out of Paris, but apparently don't want to spend time in either place. I think you wil regret this, especially Paris.

i really would consider forgetting about Greece this trip and concentrate on Italy and Paris.

this is what I would do\;

DAy 1 - land in Milan, train to Florence. stay 3 nights and recover from jet-lag.

Day 4 - train to Sorrento. stay 4 nights.

Day 8 - train to Rome - stay 4 nights.

Day 12 - fly to paris -stay 2 nights.

Day 14 - fly home.

ideally you should lose paris and fly home from Rome, but if you can't, spend at least 2 nights there is give you a feeling for what you're missing!

The flights are booked.

The night in Paris is just a layover on the way to Houston from Athens.

I am not staying in Milan, just flying into MXP and taking train to Florence

in my opinion your itinerary looks good, much better than before. have fun on your trip! should be great :)

I think is better to go only to Italy. 3 days Venice, 4 Florence, 4 Rome, Sorrento, Amalfi Cost, Positano, Capri. Greece is better another time. I did this itinerary years ago and it was wonderful. Have a nice trip.