I really like high speed trains but have you paid for them? They are great for business where you need to go somewhere and come back, but for a family of 4 they are extremely expensive. From Tokyo to Osaka ~350 miles, it's about $130 per person each way on the Shinkansen. For 4 of us (2 adults, a child, and a free toddler), it would be ~$650 for round trip tickets.