SPY <-> VTI, IYY, or VV will work.
IWM <-> IWN, VB, VBR
VWO <-> EEM
DLS <-> GWX
EFA <-> EFV, VEU
I think you can exchange the microcap ETFs with impunity since they hold very different sets of stocks.
Some would argue that even S&P500 etf's can be exchanged because they have different expense ratios and probably do not hold all 500 issues and certainly not in the same proportions. But I see no reason to be the IRS test case.
Look at etfconnect.com for more help. The term "substantially identical" is open to debate and has not been tested in court for these ETFs. See wash sales at Fairmark Press Tax Guide for Investors