Evaluating Tax-Efficient Investment Strategies for High-Income Earners

John is a 45-year-old high-income earner working as a senior executive in a tech company. He is married and has two children aged 8 and 10. John and his family reside in a high-tax state, and he is currently considering various investment options for his portfolio to help fund his children's college education and save for retirement.

As John's financial advisor, you need to evaluate the tax implications of his investment choices. Discuss the importance of tax-efficient investment strategies in private wealth management, and identify specific strategies that would be suitable for John considering his income level, family situation, and tax considerations.