Best round trip from Singapore

please assist me the best round trip to cover Tokyo , Osaka, Kyoto & Nara in terms of transport and accommodations for
a group of 7 persons travelling in December 2014

thank you

If you haven't seen this, there are some possibilities here: http://www.japan-guide.com/e/e2400_tokyo_19.html

omit accordingly.

As for acommodations, just find business hotels which have rooms for 4 and 3 people.
As for your itinerary, those areas are not really advisable to be visited by car. I don't know for how long you'll stay but if you enter and depart from Tokyo then a 7 Day Japan Rail Pass will make sense. If not, I don't think any kind of pass will make sense. For Osaka, Kyoto and Nara I would establish Osaka as a base and move around the other cities in day trips.

I agree with Aerond that Osaka would be a good base. As transportation cost can be expensive, you need to establish where you want to go and which type of train pass you need. The train passes are a steal. You should stay at hotels within walking distance of the type of train pass you are using. If you purchase the JR national train pass, by riding on the Shinkansen, you will be able to visit faraway places and return within the same day. Make use of Hyperdia to gauge the time you need to travel to your places of interest. There are so many places worth visiting other than those you list, you can find out more by borrowing a Japan Guide from the National Library. In comparison to Singapore, Japan is extremely affordable and you will certainly have a good experience. Have a good holiday and you should plan for at least 10 days. The forum questions and answers in this guide will also provide you with lots of information