Thank you all very much for your input. In response:
We each have a 21-22" roller and a briefcase.
We prefer trains, metro, buses and walking. They are usually quicker and less of a hassle and generally more fun.
We are NYC natives so subways and confusing signs dont scare us. Having said that we also have enough common sense to avoid areas we have been warned about and certain modes of transportation very late at night. Personally I do not take offense when a non-New Yorker expresses concerns about the subway. I do not perceive it as a slight in any way. There's a certain reputation out there...deal with it.

At this point we narrowed our choices to:
1. taking a taxi
2. taking Roissybus to Opera and walking (thank you Michel)
3. changing to a hotel near the RER St. Michel area.
*We will be spending the majority of our time in the Marais and the Latin Quarter/St. Germain anyway so it makes a lot more sense. We could then to take the RER to/from CDG, and walk to a hotel.

My vote is for the #3.

So, can anyone recommend a hotel with A/C rooms and private toilet/showers in that area?

Thank you again

It doesn't sound like you think the RER and metro from the airport will be fun, though. It's not fun to me.

YOu don't have to take a hotel ner the ST Michel RER, there are other stops, like Luxembourg. No one seems to want a hotel near Denfert (I admit there aren't a lot of great ones right around the stop, nor too many near Port Royal, although there is one budget one near there I know--Hotel Pierre Nicole).

I'd choose Luxembourg stop myself, would never stay near St Michel. But I hate it down there. There are quite a few nice hotels near Luxembourg.

We stayed at the Renaissance Paris Vendome a few years back and we took the Roissybus to Opera and walked to the hotel with the same amount of luggage you have. It was easy.

We really did enjoy the hotel too. We got an upgraded room even though we were there on points, and as a Marriott Plat got free brekky too. It was a very good spread each morning in Pinxo.

Do you have status at Marriott? It really is a nice place,and close to the metro, but if you are paying out of pocket and not using points it would make sense to stay where you will play.

I don't think it's a myth that Chatelet has more crime than many other stations. I have seen the official statistics of crime in various stations and arrondisements, aned I think it definitely does. But some of that is just because it is so big, I think. There is always more crime in the bigger stations and where there are more tourists.

Given your concerns and where you are staying (if you stayed at your original), I would have thought getting out at Gare du Nord and then a taxi to your hotel not too bad a choice. Now the taxi queue at Gare du Nord can be a bit long, though, so maybe you don't want the hassle. But it might be less hassle than transferring to a metro line and then walking from the stop to your hotel, so it's all relative. Walking from the opera is a big of a hike.

If it were me, I wouldn't stay in that hotel.

If you stay near Saint Michel, you probably won't see much of Paris. People who sleep in the center rarely stray from the center, and that is an outright shame.

Kerouac, this is not our first trip to Paris.
We are centering our trip in the 5/6E and the Marais which we did not see last time.
I am assuming we could walk these areas if we stay near Saint Michel RER and we could easily find great cafe's (affordable) in this area as well.
I thought about Denfert but that would not be as walkable as the Saint Michel area (at least I think...).
Is there anything wrong with the RER Saint Michel area?

Renaissance Vendome sounds like a wonderful hotel however we only have 2 days and we need to make the most of it.