I want to wait until cab can snag the seats- since availability on the flights is limited.

In a word, though, I've said here and in the NW forum that proper planning can yield more mileage from a mid-con than from a transcon. In this case, I looked at PHX-IAH plus 1091 IAH-CLE and 500 CLE-xxx which yields more than PHX-IAH plus 1000ish IAH-FLL. This is given that the PHX-EWR nonstops aren't available for these dates.