For the first time I made UA silver as well as SE. I did so largely to gain access to economy plus seats on UA as well as 100% value on UA instead of 50% if in credit to AP.

In the past I've used my AP to get into UA flights in order to get free bags and lounge access. Then I get the gate agent to switch my BP to MP. This has worked well.

This year I want to do the reverse. Check in with MP to get Economy Plus but am unsure about lounge access. Will I still get lounge access in the US and Canada with a MP boarding pass? Will my card override this? This is particularly an issue in YQR where you scan your BP for entrance.

If I can't, I suppose I could switch to AP after check in at the gate but would rather have the UA full miles.

Anyone else playing in both worlds? Any thoughts on why you would or wouldn't do both?