Actually, travel must be completed by 5/31.

DEN looks doable:

OUTBOUND
Sat 16 Apr 2011
9:15am MSP
10:25am DEN
Nonstop2h 10m
DL 1708
Economy (T)

RETURN
Sat 16 Apr 2011
1:26pm
DEN
4:21pm
MSP
Nonstop1h 55m
DL 2108
Economy (T)

Cost: $159.40 - $100.00 = $59.40
Miles: 1,386 (flown) + 295 (5X AMEX promotion) miles = 1,681
CPM: $.035

Is this a good deal?
I have never personally done a mileage run, but this seems okay.
The certificate was a freebie from AMEX.