If you're at the Conrad and use the yamanote line, your use of non JRlines might be extremely minimal. If I was in your position, I wouldn't be able to make the NEX Suica option pay. But that's me. YMMV.
(We're talking about a difference in price of about 2,000yen (4,000yen for two), many people would be happy to pay this for the extra convenience and flexibility the SUICA/NEX package will offer, I just happen to be extremely budget minded)

Unless you go to Haneda airport, it is unlikely you'll take the monorail. The yurikamome line (a driverless train) goes to Odaiba, and I understand that this is fine for use with the SUICA card (as is the monorail). SUICA option is more convenient, but probably won't save you money. The difference, however, is minimal.