All UA fares provide at least 100% miles per mile flown when accruing to UA's MP scheme.

You'd have to double-check Aeroplan's rules for accruals when flying UA. I'd suggest you cruise over to the AC forum.

AFAIK, you should be OK with those UA booking classes, accruing 100% miles with a 500-mile minimum,unless you are booked on UA flight numbers UA2000-2999 or UA5000-5199. This info from BlondeBomber's Star Cross-earning Chart (a link for it is in BlondeBomber's sig line, so just find any of his posts for it).