The Hop On/Hop Off bus can be a good way to get a feel for the city on an initial visit, especially if you are jet-lagged on your first day. But I agree with others, I would not use it for general transportation. If you wish to use the "skip the line" feature check to see if it only applies on the day of your ticket validity. If so, maybe pick one venue, such as the Louvre.
For getting around, the Paris Métro and bus network is fantastic, but also get out and walk. It is a fantastic walking city, like London, Rome and NYC. With only 5 days, and one of those a visit to Versailles (definitely recommended) and another on the HOHO, you will probably stay within zone 1 for the other days.
In that case, consider getting Metro t+ tickets, rather than a Paris Visite card. IME, you really need to take multiple trips each day on a Paris Visite card to make it worthwhile. IMO, it is much more flexible (and usually cheaper) to purchase a 10-ticket carnet (pronounced "car-nay") for 14.90€ (versus a single ticket of 1.90€). You also don't need separate passes for each person. Just tear off a ticket for each person for each trip. Each ticket is good on any day for multiple transfers within a 2-hour time limit. You can use the tickets anywhere in zone 1 on the Métro, buses or RER. You can always buy another carnet, if you use up the first one. You can purchase them from ticket booths or vending machines in any station and at many retail locations.
In five days you will be pressed to fit everything in. Over the years, I have spent in total almost a month in Paris and still have not seen everything I want, if that is even possible. But a Seine river cruise is highly recommended to give you another perspective on many of the city's great monuments. While a dinner cruise is enjoyable (Paris is the City of Lights), a shorter day cruise might be better this trip.
A trip up the Eiffel Tower gives you a good vista of central Paris, even at the first level, but I recommend going to the second level. The very top (third level) is quite small. If you have a fear of heights, like my DW, not recommended to go to the top. You will not likely have time in your short visit to go both in day and at night, due to the lines. I would recommend during the day, but come back to see the Tower in the dark, since there is a light display on the Tower for 5 minutes every hour on the hour after sundown. I particularly enjoyed seeing it from the right bank of the Seine.
Another must see, that also has a great view of the city, is the Basilica of Sacré-Coeur. You will have seen it from the Eiffel Tower viewing platforms and now you get to look back and see the Eiffel Tower and the rest of the city from a different perspective. It is also a beautiful church. And you can use your carnet ticket from the Métro on the Montmartre funicular to get there from the Métro station.
If you choose to go to the viewing area from the Dome on the top, be forewarned there are no elevators. It is about 300 steps to the top, not counting the steps to get to the ground-level plaza, if you choose not to use the funicular! Another great vista point in Paris is the top of the Arc de Triomphe. You get great views down all the radial arms of major streets that converge on Place Charles-de-Gaulle (Place de l'Étoile). It is also fun to watch the maneuvering below of the traffic as the vehicles enter, circle, and exit the traffic circle around the monument.
I love both the Louvre and the Musée d'Orsay. They are very different. You will have to choose which you might prefer.
The Louvre is an ancient palace with Old Masters and antiquities and is so big, you cannot possibly cover it in one visit. One of my favourite parts in the Louvre is the Galérie d'Apollon, a spectacular hall in its own right, where the former Crown Jewels of France are located, together with many exquisite masterpieces of metalwork and jewels.
The Musée d'Orsay is much more modern and bright inside, with its large expanses of glass. It is a much more recent and beautifully executed transformation of a former rail station, now holding the works of the Modern Masters. And with respect to photography in the Musée d'Orsay, it is now permitted again, as long as you are not using flash or a tripod. General photography was only banned from 2009 until 2015.
With all the other things to see in Paris in a short visit, you will not likely get to all of these spots. Also, there are many other places we haven't even touched on. There is so much to see: wandering in the Tuileries and Luxembourg Gardens and surrounding areas, the Paris Opéra (both old and new), Notre-Dame, Place Vendôme, Place des Vosges, the Marais, Parc Monceau, the Champs-Élysées from the Arc de Triomphe to the Tuileries and so much more. The list goes on and on.
There is so much to see and do in Paris. You can only start to chip away at it in 5 days. Enjoy your visit.