eiffel tower

If you are going in early November, I believe it will be just after sunset at 5:30 pm, so pick according to your schedule, before dinner or after dinner. Best way is by Metro, although there is no Metro stop right by the tower, Ecole Militaire is a short walk through the park Champ de Mars. From St Lazare, take the No 13 line to "Invalides" (direction Chatillon Montrouge) and change to the No 8 line (direction Ballard) and get off at "Ecole Millitaire".
Its a 3 km walk from St Lazare, and it is a nice walk if you are so inclined.

I don't know exactly where your hotel is but if it is the vicinity of St Lazare might you be on the side where you could have an easy stroll down to Place de la Madeleine? Or Opéra? If so you can hop a number 42 (dir Hopital Européen G Pompidou) to Tour-Eiffel. Simples. Can I suggest that you get the right maps and knowledge of the RATP website, Teo? It will be much better for you to be able to sort out Paris transportation yourself when you need it instead of needing somebody to show you the answer each time. You'll save hours.

I was going to suggest Bus No. 42 as well, Nigel. Her hotel is on rue Amsterdam. Teo, ask at your hotel, and get them to show you on a map, the best way to the closest stop for Bus 42. It stops very close to Gare St. Lazare's front end. Get off the bus at Champs de Mars and you will see the Eiffel Tower on your right. If all else fails, take a taxi!

In that case the nearest stop probably is Opéra-Scribe. The southbound 42 runs down rue Scribe into Boul des Capucines before Boul de la Madeleine. It never get closer than that to St Lazare. Is it the bottom of rue d'Amsterdam?

Teo, I would learn the subway system in Paris As Soon As Possible (ASAP) because you will use it. Yes, you can hoof it, but its nice to use the subway to save on the wear n' tear. I found the Paris subway system really nice and easy (in my limited opinion) to use. if i were to go from your hotel to the Eiffle Tower (ET) by subway, i would use the #9 and get off behind the Trocadero. Its a nice walk down hill and you would get a great view of the ET from near the Trocadero. But thats just me. The Ecole Militare stop isnt that bad either and you get a chance to walk thru the park. happy trails.

Teo, Your hotel is located close to Saint-Lazare station, so quite a distance from the Eiffel Tower. IMO, travel by Metro would be better than travel by Bus at that time of day, as traffic could be "thick". The Metro will be busy too, but at least it's not affected by traffic. The route I'd use is Line 13 from Saint-Lazare Metro station (direction Châtillon-Montrouge) to Invalides, where you'll transfer to Line 8 (direction Balard) to École Militaire. Under ideal conditions, that trip should take 24-30 minutes each way. Another option would be to transfer to RER "C" at Invalides (direction Versailles / Saint Quentin) and disembark at the Champs de Mars / Tour Eiffel stop. I'd probably stick with the Metro only route, and walk from École Militaire. It's only about a 10-15 minute walk. If you buy a Carnet of 10 tickets, those will work for the trips you're making. However, note that they're only valid for a specific period of time after being validated in the turnstiles, and if you exit the system, you'll have to use a new ticket. Cheers!

I have a love-hate relationship with the Paris Metro but it is the most efficient way to cover a lot of ground. Just keep looking for and following the signs to your Metro line connection. Even with my limited French, I was able to get directions from the metro staff when I needed them (which was often). They have a good map of Paris that shows metro, bus, and RER routes, ask for that before you board your first metro. Once you're on the metro, it's very easy to figure out where to get off.