I suggest you pick a carrier, in addition to Midwest Express, like UA. As I recall, Air Wisconsin (t/a United Express) flies from Appleton to DEN and ORD, so that should work well enough.
Write UA Mileage Plus, explain that you plan to fly 50k+ miles this year, send a copy of your status with Midwest Express, and they will likely comp you to 25k or even 50k elite level, then you can start to fly UA and get upgrade "coupons," etc. for trip to HNL...
Just my 2-cents.
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