All of the currently scheduled DTW-IAH flights are CR9's or 319's.

IMHO a CR9 is not a regional jet. yes it technically is but I would not put it in the category of a CR2/7 as it has roomy & comfortable seats & an F cabin.

Similarly ATL-IAH is also CR9's and M88's. I personally prefer the CR9 over most planes but the M88 on those shorter flights. It's comfy (IMHO) and an almost guaranteed upgrade.