I used an online tool to calculate the estimated taxi fare from the different stations to my hotel and it is about 500 JPY more from Tokyo station. Factoring in time, cost of tickets and cost of taxis, I think we will just arrive at Tokyo Station and take a taxi.

Thanks for all your advice...has been very helpful! Now I just have to figure out if it is worth getting a subway card or just paying as we go for tickets!

Don't bother with a subway card. If you are travelling to Tokyo (and back) by Narita Express get a Suica & N'EX.

To answer this one, anyone with a *valid resident status re-entering Japan from dependents, students, workers to permanent residents (excluding temporary visitors) can use the re-entry lanes.

*(re-entry permit holders for trips over 1 year or deemed re-entry for trips out of Japan lasting 1 year or less)

From my experience immigration is pretty efficent at NRT in processing times.

Best case for NRT immigration for me has been no wait. Worst case is 60 minutes. It really pays to move as quickly as you can from the plane to the immigration area, it can save you 15-20 minutes in the worst case.

We are departing from HND so the NEX + Suica card does not make sense. Is it worth getting a Suica card for the few days we are in Tokyo or are we safer just to pay as we go?

If you're taking the N'EX from NRT, then the N'EX + SUICA combo is basically giving you money. The cost benefit is outlined on this page:
http://www.jreast.co.jp/e/suica-nex/

If you really hate the idea of using a SUICA, you could hand the card straight back and request a 1,790 yen refund. (1,500 yen credit + 500 yen deposit - 210 yen processing fee). That's right - By paying an additional 560 yen, you've picked up a card that's worth at least 1,790 yen. A savvier customer will get 2,000 yen of value out of that card. To do that you need to use the 1,500 yen credit and hand back the card for a full refund of the deposit (no processing fee payable on that).

Of course, if you see a train that's about to depart and there's a long line for purchasing NEX+SUICA combo, you might decide that it's not worth it ... I can understand that. But I don't think that's a judgment you can make until you're at the station.

The only downside that I can think of in using a SUICA card is that you need to use it all up and get your refund at a JR window before you take the train to Haneda. AFAIK, there's no JR counter at Haneda airport, so you have no way to get a refund there. (Someone will correct me if I'm wrong).

The main upsides of using a SUICA card are that you never need to pore over the confusing subway maps to work out fares, you don't need to visit the fare adjustment machines (unless your SUICA runs out of credit), you will find it extremely easy to transfer from one railway company to another, and you will not spend time faffing around with coins and notes at ticket machines.

YMMV

So we can pickup the One Way Suica + NEX for 3,500 JPY at NRT. We can then return the Suica card for our 500 JPY refund, less 210 JPY processing if any money is left on the card.

So basically for 3,500 JPY we are getting a one way NEX ticket (2,940 JPY value to Tokyo) and 1,500 JPY on the Suica card + the potential refund of 500 JPY. Seems like a great deal!

Where would we refund the Suica card to receive the deposit back?

How do I figure out which lines we can use it? We are staying in Roppongi but I do not see that station on the map on the website.

Go to the ticket counter of any JR East station.

It's valid on almost all subways, JR lines, and buses. You can also use it in some vending machines, taxis, convenience stores etc.

Roppongi is served by several subway stations. No JR station.

So would the Suica work at one of the stations?

I guess its a good deal so I might at well take it. Thanks for the advice!

AFAIK, it works on all subway lines.
There are some buses which won't accept payment by SUICA - e.g. the airport buses, and some little local services. Also, you can't use it to ride on Shinkansen services (e.g. from Tokyo Station to Shinagawa). Perhaps some other people have more examples of the cases where you can't use SUICA.

Well, it doesn't really make sense to me to back track from Shibuya. Also Shibuya's NEX platform is next to New South Exit. If you exit there (easy and not crowded) then there's no official cab rank. Sometimes I see a few cabs line up (blocking the road) there early in the morning, I think (I drive by frequently when taking a back street short cut) but usually not.

The two times I took a cab from NSE then I happened to grab one that was discharging a passenger and the other time I had to walk out to Meiji dori and hail one. This is still a better option that walking through the station, crossing 246.

The cabs at the east exit of Shibuya are heading the wrong direction and maybe can't make a legal right turn up to 246. At the west exit a cab can make an easy left turn onto 246 and head to Roppongi.

I guess Shibuya is a bit closer to Tokyo Midtown.

It is actually 900 JPY to the Yaesu area of Tokyo Station !

My only reservation is that Tokyo Station is very complex and the OP might spend a long time finding his/her way to a taxi rank.

N'EX platforms are marked "(B5) Sobu Line Platforms (Basement Level 5)" at the bottom of this map and the best place to get a taxi for Tokyo Midtown will be the Marunouchi Exit of the station, which is at least on the right side of the station complex.

It really is quite simple to get off the N'Ex go up two escalators to the ticket barrier level, pass through the barrier, and look for signs for Marunouchi North Gate. There is an elevator adjacent to the stairs (a left handed baseball throw from the ticket barrier) if people have luggage. Once outside at street level stand still and look for the taxi rank sign.

There is less walking to a tax from the N'ex platform than there is at say SFO when deplaning from a domestic flight.

From Tokyo Stn. to Midtown is a straight line with no doubling back. Clearly the most efficient way to do it.

Not even remotely difficult. Hot as heck yes, but not hard. :-)

I'd probably take the bus to ANA (if you don't have to wait too long for the departure). ANA is the first stop, traffic should not be too bad, and it's a quick easy 5 minutes cab from ANA to the Ritz.

As others have suggested NEX to Shibuya is a good option also.

NEX to taxi (Marunouchi North Exit) is easy if you know what you're doing but can be confusing.

Another option if you don't have much luggage is NEX to Tokyo, transfer to Marunouchi subway line (very easy), two stops toward Shinjuku, transfer at Kasumigaseki to Hibiya line for Nakmeguro (extremely easy transfer.....50 meters from the front of the Marunouchi line platform), two stops and get off at the rear of the platform at Roppongi, go out exit 4a. From there a 250 meter walk to the hotel. (This is the cheapest and quickest option).