i suggest just doing a search on orbitz or some other website that has multiple airlines to see the number of flights per day to each, then make your decision.

as for the parking pass, most companies will reimburse you for a parking pass out of domicile only up to the cost of the pass in your base. so if the pass in MSP costs $100/yr, then they'd only reimburse you for $100 of the pass at ORD, unless the ORD pass is cheaper, then you get the cost of the parking pass