Traveling to Lake Como or Garda, do I need a car?

We flew Minneapolis-Amsterdam-Milan and then took the train into Milan and a different train to Varenna all in one continuous journey. We walked and used the ferry at Varenna. If I remember correctly, the biggest issue we faced was finding where to find the tickets from Milan to Varenna. We went downstairs in the train station to buy them. We didn't find it too exhausting, and by the time we got to Varenna it was check-in time at the hotel.

did you read Rick's advice on visiting the lakes?

LAKE COMO:
If you choose Lake Como, you don't really need a car. Fly to Milan Malpensa (MXP) then take a train from Milano Centrale to Varenna-Esino (trains final destination is Tirano, therefore the signs on the platform at Milano Centrale will display Tirano). To reach Milano Centrale from Malpensa airport take the Malpensa Express Train. Make sure you take the train that goes to Milano Centrale, because there is also the Malpensa Express that goes to Milano Cadorna station.
For the lake choose one of the following locations in the Mid-lake to stay: Varenna (this one is where the railway is), Menaggio, Bellagio. Varenna is where the train goes, but the others are easily reachable from Varenna via short ferry ride. The midlake is best, and these 3 towns also have the ferry shuttle, which is a very frequent ferry that connects the 3 towns.

LAKE GARDA:
The train at lake Garda touches only the south shore and stops at the main towns in the South shore: Desenzano and Peschiera. I personally prefer the North part of the lake, which has majestic mountains (the southern side is flat plain). The best way to reach the north side is via bus from the aforementioned towns or also from Verona, the provincial capital. Garda is Italy's largest lake and the ferry trip from the south to the north takes some time, but one could use the ferry as well. Personally I think Garda is best by car for a variety of reasons. The north lake is more convenient to reach since the train does not go there. Also the car would allow you to visit things that are best done by car such as the 'Strada della Forra' (road of the gorge) and also the nearby Dolomites mountains, or the Valpolicella wine region (if you like wine). Lake Garda also features a driving safari (NaturaViva) and Gardaland (theme park) in case there are kids in your party. Both need a car. The problem that I see in your case is however the fact that you have 7 people. Those are hard and expensive to accommodate in one vehicle. A 7-9 seat van costs as much as 3 economy/compact cars to rent, which makes it expensive and also inconvenient if you have a lot of luggage. If you decide to rent a car I would probably do it at the airport where you land and drive there directly. The closest rental car offices to Lake Garda are in Verona, about 1+ hour drive west of Venice airport and a about 2.5 hours from Milan Malpensa. If you don't want to rent a car and choose Lake Garda, I recommend to take a bus from Verona to Malcesine (in the north lake) and stay in Malcesine. You could also book a limo service from Verona or from Venice airport (although it would be more expensive, albeit more convenient). Malcesine is very quaint and has several boat options to nearby towns on the lake, like Limone, Riva, Torbole, etc.

One added option:
LAKE MAGGIORE
If you land at Milan Malpensa there is also the option of going to Lake Maggiore, which is very close to Milan Malpensa airport. There is a bus from Malpensa airport to Stresa, on the lake. Alternatively you could go to nearby Gallarate (15 min from the airport via taxi) then catch a train from Gallarate to Stresa. The bus would be more convenient, but it's not as frequent as the train. You can also rent a van at Malpensa and drive the 45 min to Stresa yourself, or secure a limo service (a van) which can take you to your hotel in Stresa).

Once you decide which lake, you can ask us more questions on the details.

You can get a through ticket from MXP airport to your final destination at the Airport station, no need to make 2 separate purchases in two stations.

It's true that at Milano Centrale the manned ticket counters are downstairs, but there are dozens of ticket machines in the tracks area or just outside. Varenna station is listed as Varenna-Esino.

Thank you for all the good information. I am having difficulty finding a proper accommodation in Lake Como for 7 of us, but am still looking. We are 4 seniors and 3 young adults. There is some limitations to mobility, and I have some concerns about properties with steep climbs.
My question is regarding Lake Garda. I would prefer to stay in the alpine north side of the lake, and have found nothing in Malcesine that works. Is anyone familiar with Torri del Benaco? There are some good possibilities there, is this a more alpine or Mediterranean climate? Thank you!

we have decided on Lake Como, and found a place to stay in Menaggio. I was thinking to just get a cab or limo from Malpensa for the drive to Menaggio. There may be 5 people, but possibly 7. Should I book something in advance? Can you recommend a company to use? Grazie Mille!

Don't have companies to suggest in Milan Malpensa, but you can search using the key words NOLEGGIO CON CONDUCENTE (or just NCC) followed by Malpensa. Noleggio con conducente means 'car hire with driver' and it is the technical term for any limo service/private driver company. There are several that operate from/to Malpensa and you can start by doing some research and maybe get some quotes. Here are two major ones. They charge about 150-160 euro (for 3 passengers, probably a bit more with a van for 7 people).

https://en.taxi-airport-malpensa.com/taxi-malpensa-menaggio
https://www.taximilano-malpensa.it/taxi-malpensa-menaggio/

PS: Torri del Benaco is ok. The climate on the lake depends on the season. It's not alpine because the lake surface is only 65 meters above sea level (210 ft). So in summer it's not cold. But the lake is notoriously kissed by the wind (it's a major wind surf destination in Europe), so you shouldn't be too hot.

You can go up and down the lake by bus. Although there are also boats.
http://tech.atv.verona.it/atv_www/orari_extraurb/pdf/484.pdf

Thank you for the information, I will post something about the cab/limo hire when I have booked something.