Activities and Travel in Paris, France

For Napoleon you can visit Château de Malmaison in Rueil-Malmasion, a western suburb of Paris and reachable with public transport. I suppose Arc de Triomphe is already on your list.

Mass transit in and around Paris sets its fares according to zone. You likely will spend most if not all your time in Zone One and Two. The easiest ticket choice is a "carnet" which is a little package of 10 individual tickets, very low-tech. You can find out about fares at the very useful RATP transit website http://www.ratp.fr/en/ratp/r_61656/t-ticket/ One ticket in zone one costs 1.80 €; a carnet of 10 costs 14.10 €. Metro and RER trains are interchangeable in the core. Plenty of municipal buses and several street rail routes. No transfer from underground to above-ground transport, though.
As to enjoying yourself, the Destinations sections of this and other similar travel-guide websites offer a huge selection of activities as do the various municipal and other government information sources. DIY to satisfy your particular tastes.

As noted above your best bet is a carnet of ordinary metro/bus tickets which will take you anywhere the metro goes including where it occasionally laps into zone 3. For longer trips e.g. Malmaison (and that is a great suggestion with your interest in Napoleon) you need specific point to point tickets for the RER. These tickets are priced per trip not zone although higher zones are generally more expensive, there is not a 'zone ticket'. We learned this when we visited a site in Zone 4 and then walked to the next village and planned to return via RER and our ticket to the other village would not work. So any travel outside Paris needs a destination specific ticket which is easy to obtain on machines in the metro; get two for going and coming as there is not always a ticket agent at outlying stations and machines often take only coins.

The only pass that would actually work for your visit is the Paris Visite which is a much overpriced tourist product.

You might want to visit the Carnavalet museum in the Marais which houses French history items including a couple of bricks from the Bastille. What remains of the Revolution would be housed there. Another spot to visit would be St. Denis Basilica which you can reach on the metro. This is where the kings of France were buried and while during the Revolution their remains were dug up and thrown in the Seine or in pits, the magnificent tombs were saved by a revolutionary who marked them as art objects, which they are. The remains have supposedly been returned to a mass grave at the Basilica but in particular the tombs of the murdered King and his family are there. You can see my snapshots in my photo journal at:
https://janettravels.wordpress.com/2010/10/26/confronting-mortality-at-st-denis/

The 'Napoleon apartments' in the Louvre are interesting but they are not the apartments of the Napoleon you are interested in but his nephew the last Napoleon to rule.

I would think Fontainebleu would be on your itinerary. The chateau itself was used by Napoleon and there is a Napoleon museum there.

"I'm not really interested in a tourist trap ride down the Seine."

Just because you have no interest in it does not make it a tourist trap. If only Napoleon had done it.

Carnet is the way to go for Metro and RER, also busses which take longer but show you the city.

Paris Walks offers a "French Revolution" walking tour on Tuesday afternoons, showing you various Left Bank sites that figured in the revolution. It doesn't include the Bastille which was on the right bank and is now just a traffic circle with a monument. It does include a model guillotine on which the real one was based, now in a cafe in the Latin Quarter. I didn't see a Napoleon-related walk but they might have one. The guillotine site is now the Place de la Concorde (formerly Place de la Revolution), which you're bound to see as it's pretty much in the middle of everything. Besides Napoleon's tomb, the Invalides houses an excellent military museum with a lot of Napoleonic stuff. I remember a summer sound-and-light show featuring him in the Invalides courtyard. Fontainebleau would be a good day trip but with your short timetable maybe not possible. The Carnavalet Museum is a good idea too, in the Marais.

What else to do in 2+ days of sightseeing, sans romance or river cruise or ET? Between the Revolution and the Emperor you'll probably fill up the time. Stop in a café, stroll through a park, cross a bridge, be glad you can return to the city again and start planning your next trip!

Purchase carnet of 10 tickets to ride the metro or bus -- very inexpensive.
Do Les Invalids, and the Army Museum for your Napoleonic tour, and also Fontainebleau -- if you have the time.
Go to St. Denis basilica, i the final resting place for the kings and queens of France. Fantastic sculpture, stained glass.
Also, the Carnavalet museum is great for revolutionary history. It's one of my favorite museums in Paris. Is free and not crowded.
The guillotine was installed at the Place de Concorde, which today has a beautiful fountain, and usually has a Ferris wheel operating there. If you like Ferris wheels, going on it at night should give you a great view.

I love the walk from the Louvre, through the Tuilleries gardens, ending up at Concorde. It's a great Parisian strolling place, if you like people watching.
You should see the light show at the Eiffel Tower that goes on hourly at night, if you haven't seen it already.
I suggest the restaurants and bars of the Marais, if you like a bit of night life.

The Ferris wheel at Concord goes up in mid November and is only up over the Christmas season; it is not generally available at other times of the year.

Thanks to everyone who replied. I ended up buying a Paris travel pass for the 2.5 days I shall be in Paris.

Napoleon was out of town a lot, fighting all those battles. I see (from another thread) that you're going to Waterloo. That wasn't Napoleon's favorite battle, maybe you could go to one or two of Napoleon's victories.
And to Fontainebleau (30 miles south of Paris) where you can see a tent he used when he was out of town fighting.
And the Waterloo car rental you mentioned in your other post, maybe you could practice driving a stick shift, it will make renting a car in Europe easier and cheaper.
But Napoleon couldn't drive a stick either.

Make sure you are not late for your Eurostar trip. It is upstairs, slightly hidden, at the Gare du Nord.

The queues to check in there are infamous, and if you are not checked in 30 minutes prior to departure, with security and passport control after you check in you won't be allowed to travel.

My advice recently has been to be at London for check in at least 45 minutes and closer to an hour before. Based on the queues I saw in London last weekend, with an overflow queue in the next concourse, is an absolute minimum of 60 minutes. I'd now be there nearly 90 ahead.

My advice has recently been an hour at Paris. I'd up that some now.

The last time, last year, that I returned from Paris I nearly didn't make it. I'm experienced on the route and was there nearly an hour ahead and made it by about 10 people.