Originally Posted by
SFO777
If most of your travel is domestic and you're not using CLE as your main hub (i.e. IAH or EWR), I would definitely go for it. You will be virtually guaranteed upgrades on all but a few routes. Plus once you have your CO Plat, most other airlines (UA, DL, NW, AS, US but not AA) will grant you matching Platinum status just by asking.
DL won't match status on CO. I would be very surprised if NW does, though you don't need it on NW as your CO status works there.
I think you might have it backwards: I have found CLE to be much easier for upgrades than either EWR or IAH.