If you move chunks of your ETF portfolio into a Claymore bond fund ETF (I like CBO), you can utilize the SWP (systematic withdrawal program) to withdraw funds periodically without paying a commission. Your broker may charge a commission to withdraw the funds from your account. If they do, I recommend switching brokers.
Otherwise, you can just make trades every quarter (as part of rebalancing, etc.), withdraw your allowance for the quarter and put it into a high interest savings account. I wouldn't sweat the commissions, unless you're with an expensive brokerage, in which case the problem is the brokerage, not the ETFs.