Big Bus Hop On Hop Off or City Public Transport?

Public transit will be much less expensive than HO/HO buses, and it usually runs more frequently.

Rome's subway system is more limited than might be expected for a city of its size, so there may be times when a bus works better.

The free Citymapper smartphone app will provide step-by-step directions via city transit for trips in Rome and Vienna. It doesn't cover Salzburg at this point, but the part of Salzburg usually visited by tourists is rather small.

We love the big bus hop on hop off tours as a way to get oriented to the city and see everything. We usually stay on for an entire loop for the first time . We combine the tour with walking and public transportation. From example, we may get off the hop on hop off bus at one sight but then do public transport to the next

Will only comment on Rome - The Hop On hop off buses can't cover the most interesting parts of Rome, the streets are too narrow & public transport is cheap and easily available. You can take trams, buses & hey taxis are reasonably priced too! If you're only in Rome for 2-3 days, I would look carefully at 1) Where you're staying 2) Your must sees 3) Time management. Personally, I would grab some taxis so you can actually see what you want within your time frame. (It was around $10-12 for a taxi ride of 20 minutes, hardly the most expensive part of travel.) You could take the bus for an overview of the Forum, Colosseum & Vatican in the evening, the lighting is amazing, but it's not the cheapest way to get around.

Here's my recent Trip Report, assume Rome will be jammed in May, get out early to avoid the crowds and enjoy, it's a fantastic city! https://community.ricksteves.com/travel-forum/trip-reports/rome-was-jammed-over-ny-but-still-fun#bottom

I haven’t done a HOHO in Rome. In other cities I have used one and done the complete loop and then used it to get to 1 or 2 sites.

If you are used to all that walking, then I think that a combination of subway and walking will be just fine for you

If you only have a few days in each city, the choice of lodging should be strategic to afford greater access to the sights you intend to see.

Vienna is quite compact, mass transit inexpensive [one of the cheapest trips to the airport that I've ever seen] so you should be able to get around with judicious use of subway and tram - the RS guidebook can give guidance on where to stay.

In Rome, the Metro serves specific areas, and can be useful getting to/from the Colosseum & Forum, as well as the Vatican, if you're staying near a Metro station. It takes research to use the bus and tram system effectively - keep in mind that streets in Rome aren't on a grid layout, so routes aren't straightforward. Metro/bus rides are inexpensive, and you can now pay with a contactless card. As others may suggest, taxis can be useful in Rome - and many say that hop on/off not practical in Rome. But walking is often the best option.

This information is very helpful. Thank you so much for all your replies! :)

I like using the Hop On/Off busses, especially when we are in a place for the first time. Last time we were in Rome, we took our child for the first time. It is a great way to get an overview of the city.

IMO, most of the famous attractions are far apart in Rome. As others have mentioned, busses and taxis can save time and be less expensive overall. Whereas the tourist busses are more expensive and require you to circle the city.

It depends on what your plans are for Rome.

Public transportation will be cheaper than HOHO buses.

The HOHO buses I have taken were a one way route. Often the entire route takes over an hour. Buses were often not running on schedule, the stops were hard to find, or a bus just skipped a stop with us standing there. So this is neither convenient nor time-saving.

I would check to see if there are apps for the metro/bus systems in each of the cities. This makes getting around so much easier. Also see if there are group passes or multi-day passes available to save some money.

In Rome a single Metro/bus ticket costs 1.50 euros. It's good for 100 minutes and includes transfers, but you can't take the subway, transfer to a bus, then transfer back to the subway without using another ticket.

There's a 24-hour pass for 7 euros, but I think it would be the rare visitor who took 5 or more rides in one day, which is what you'd need to do in order to save money with a pass.

The 48-hour pass costs 12.50 euros (requiring 9 rides to save money--extremely unlikely).

I believe you can now use a tappable credit card at Metro gates rather than using a pre-purchased, stored-value card or single-trip ticket. I'm not 100% sure about the situation on buses; I hope someone else can confirm tappable credit cards are also OK on buses.

Buses can’t drive into Rome’s historical areas, too cramped.
Rome-walk
Vienna- walk
Salzburg( the old town) walk

I hope someone else can confirm tappable credit cards are also OK on buses.

As I mentioned earlier, contactless cards can now be used for both Metro and buses [and trams]. On the bus you need to look for the red terminal, which is separate from the yellow paper ticket validator - it may be at either the front or middle door. Our experience on several occasions was that the credit card reader wasn't working, so we rode for free - don't know how a ticket inspector would handle that situation.

Thank you everyone for your suggestions! Looks like it makes more sense for us to use public transport and walk around.

I think you will find that that is best