How much to see?

I've been discussing my travel plans with my parents, who are advising me to look at concentrating my itinerary on a certain area rather than trying to cover as many continents as I have in mind.

In some ways I'm inclined to agree. After all I know that I definitely want to take the Trans-siberian train and get under the skin of Japanese and Chinese cultures. However beyond that I can take or leave a lot of what is in my itinerary.

Now I feel I have to think again about what I do want to see on my trip, and to some extent my reasons behind them. Am I really wanting to take in all those continents to make the map of the world turn red with countries I've visited? And am I also being taken in by the common or garden RTW itinerary that includes a lot of countries of which I'm not in all truthfulness that interested?

The alternative to my world itinerary would be to focus my time, still potentially spending as much as a year, doing the Trans-sib and exploring the lands and cultures of primarily North-East Asia which interest and intrigue me so greatly. This would be a massive alternation to what I had planned, and is going to require a good deal of thought over the comes days and weeks. However I can't dwell over it too long; the departure day for the Trans-sib is still more or less set as early May. The intervening weeks between now and then will not hang around, and I've still a lot to organise.