ITDJ
iShares LifePath Target Date 2070 ETF
stockNYSEETF

I would go with a one-fund solution, either SWYPX or ITDJ. They are both index target date funds, well diversified, low expense. If you don't want a TDF, then my next option would be one global market fund, like VT or SPGM. If you want to control the allocation of domestic to international, then two funds, one US total market fund and one broadly diversified international fund. SCHB or SWTSX for US total market, then VEU, VYMI, or DFAX for international would be my picks.