Upgrades on NW are automatic if seats are made available -- 5 days out for Plat, 3 for Gold and 1 for Silver. As a platinum flying out of DCA I am at about 95% on getting upgrades. The only ones I've missed in the last 18 months have been Sunday evening MSP-DCA or ATL-DCA (on the management -- Delta). Don't you have to use coupons or something on UA?

The WP Visa is gone. Delta has several AMEX cards.

Delta has implemented its variation of the SWU -- they are good for use with Y, B, and M fares. Platinums get 6 one-way per year.

If my home airport was MSP again (it was once) I can't imagine that I'd want to fly almost every flight with a connection through ORD (mostly) or DEN (well DEN might not be too bad).