7 day Italy Itinerary help!

OUCH! Only a half day in Rome? Anyway, welcome to the forum. Members here are always happy to share thoughts and experiences. A few questions, please, to get us started: When are you planning to travel? From where? Why fly into Milan? If you are primarily interested in Venice and Florence, maybe fly into Venice and home from Florence? With only 7 days (which really means 6 nights and 5 1/2 days) I would suggest 3 nights in Venice and 3 nights in Florence (maybe a day trip to Cinque Terre). Let's start the conversation there! Enjoy the planning. Great dinner conversation!

When is this trip?
How many NiGHTs in italy?

You will need to stay in Milan night before departure so that is 1 night from your total

If you have 8 nights (which equals 7 full days) then you really only have time for 2 locations
Probably no time for a seaside location and I wouldn’t bother with a half day Rome-.
Rome needs 4 nights or more

Suggestion:

Fly in to Milan
Take train to Venice on arrival
Venice 3 or 4 nights
Train to Florence
Florence 3 or 4 nights
Train to Milan
Milan 1 night
Home from Milan

I recommend getting RS italy guide book-Amazon ships quickly

If you can change your flights
Fly IN to Venice , out of Florence

Your target cities, Venice and Florence, are several hours distance from Milan. And unless your flight home is mid to late afternoon, you would want to spend the last night in Milan to avoid any risk of missing that (expensive) flight. So you don't really have 7 whole days to explore much. 3 nights in Venice, 3 nights in Florence, and a night in Milan is about all you have time for. Half a day in Rome would be pretty much useless. By "seaside cliff beach town" I assume you mean something similar to the Cinque Terre. This would require taking an entire day from either Venice or Florence, and put you there at the most crowded time of day along with all the other day trippers and cruisers on ship excursions. So think very carefully if that would be worthwhile.

We just added this week of travel to Italy, after a couple of weeks in Portugal visiting family. Dates are in mid July. Our tix to Milan are purchased so we are stuck entering and leaving the country through Milan. I was also thinking, Venice, Florence, Cinque Terre… only mentioning Rome because it’s a bucket list stop! But it can totally be for our 2nd visit! Would be great to get ideas of where to stay (we are partial to vacation rentals but will stay in hotels) and how to best get around. Also are there low cost tours you can recommend?

You've got a lot of Italy lovers on this forum, and few would travel this fast, so just take that under advisement. The most important thing is your comfort level with this kind of travel--Have you done something like this before? How are you with early mornings and packing light? Both will be very necessary. If you want a whirlwind trip like this with a clear understanding of what it will be like, then go for it, but do consider the opposite plan of picking one or two places and taking them a bit more leisurely. PS Do get a guide book (to tackle that unfamiliarity part--that's what most of us did!) and peruse the sample itineraries--pick out what most appeals to you but try to not overdo it. Good luck!
Potential itinerary:
If a flight into Milan is booked, but you have no interest in Milan, then on arrival take the train to Florence, spend a few days, then take train to Venice, spend a few days, then wrap up with enough time in Milan to get to your flight (probably at least a day). I would save Rome for a return visit.

Is there a guide book you recommend?

I recommended Rick Steves Italy book above
You can order from Amazon

Until then
https://www.ricksteves.com/europe/italy

Most us here feel his itineraries are too fast paced

With such a short amount of time and flights into and out of Milan, I would limit your overnights to a MAXIMUM of three places. (Personally I would choose only two, plus a night in Milan)

Milan, Venice, Verona??

Milan, Florence, Bologna??

Milan, Genoa, coastal Liguria (I'd prefer Camogli over the Cinque Terre).

Milan, Lake Como

Milan, Bergamo, Lake Iseo

Personally I'd drop Florence and Rome for sure. You could fly into Milan and then train straight to Verona, on to Venice and then back to Milan. This would give you the most time in each. If you like the look of the lake district instead of a seaside town, you could start there, then move on to Venice.

YOu are also close to Turin up there, and that might be a less touristy place to visit, I haven't been myself, but it is on my bucket list!

I agree with the above comments to stick to 2 places..Venice and Florence. If you think you need a relaxing beach day try Lido Beaches in Venice for an afternoon or do a day trip from Flornce to Via Reggio.

7 days, stick with TWO places. Recommend Venice and Florence.
Forget a cliff beach town. The beaches in northern Italy are nothing to brag about and you ONLY have seven days.

Have you considered flying into Milan and out of Rome? If not, you are going to be hard pressed to hit Venice, Florence and Rome and then get BACK to Milan for your flight home. Of course I don't know the particulars of available flights and whether that is a possibility for you, but maybe check into it.

Yes, you COULD do half a day in Rome and just hit the highlights, but that would make sense only if it was the last day of your trip and you were staying there the night before you fly home.