Is it better to take the RER + metro or a taxi in Paris?

Your description is a bit rough since the Arc is not in the 17th and neither Metro 3 nor RER E get very close to it. Maybe cough up the name or address of the hotel? The taxi would be maybe twenty-five bucks max.

the hotel is the Etoile Pereire.

You've got a good bit of tunnel hiking: close to a quarter mile to get from Nord to the Magenta station and about the same when you switch from E to 3. Then again the same amount from the metro station to the hotel. The taxi is starting to look pretty good if you're concerned about luggage.

How are you with luggage and stairs? Most metro stops have a lot of stairs. There are also stairs between the metro and the RER although we found nice escalators at many of the RER stops we visited. Next, we were in Paris 6 months ago and found that the taxis were not really expensive. A couple of times we were down near the Louvre and we were at the Hilton Arc de Triomphe which is about 6-8 blocks east of the Arc. 15E wasn't bad with tired feet from walking all day. Next, the instructions do work. RER E will take you to Gare Saint-Lazare where you can change to the Line 3 Metro. From there, you don't identify your stop but Line 3 does go in the general direction of the hotel where we stayed. Once you buy your RER ticket, it will be good on the metro. Here's a link to see what I see. http://gyazo.com/f19d8c0dea2ad91ed716415393aa5c8c

Take a taxi,, it will be roughly 20 euros,, not cheap, but priceless in making your arrival easier. You will however be travelling rush hour, so not so great,, but it still worth not doing public transport with luggage. not speaking french doesn't matter ,, the lines are color and number coded, anyone can handle them,, i just think with luggage , the trains,( rer and metro) will be crowded, you will be disorientated, why put yourself through it. Take a taxi ,, from the taxi stand outside the station( do not go with a taxi driver who approches you randomly ,, go to the offical TAXI stand,, it is well marked, the taxis are properly licensed and metered) . Write down name of hotel and full address ( include postal code please) and give to taxi driver, better then miscommunicating addresss , plus many drivers now have GPS and will just enter the address in it for route)

The hotel website suggests a different route than the one you said the hotel gave you. IMO, it's the more logical one because there is only one tunnel hike. Walk through the tunnels from Gare du Nord to the La Chapelle metro station which is attached to the north end of Gare du Nord. Take metro line 2 to Villiers. Transfer to metro line 3 and take it to Pereire.

Rosemary, when you say we will have luggage, how much luggage do you mean? Can you easily handle it and be in control, or will you be bumbling along?

Thanks so much for your help everyone! The taxi is starting to sound good!

We had our hotel (Le Littre, 6 arron.) make taxi reservatins for us. We were there in 2009 and 2010. It was a set price to/from the train station or CDG. It worked out great. We were met at the luggage area or where we left the train. Maybe your hotel will make the reservations fo ryou. We just paid the driver directly. We didn't want to hassle with all our luggage on the train in an area we weren't familiar with.

I too suggest you take a taxi. When we have been in Paris, we have had our hotel make arrangements for a set fee transfer. The taxi driver met us at the luggage area a the train or at CDG. Then he helped us with our luggage and drove us directly to our hotel (Le Littre, 6 arron.). In returning to CDG, the taxi driver met us at our hotel. We liked it, as the price was a set rate and we paid the driver diretly.