Would loooooove to find any airfare/ticket shops. My guess is most of those went away when COVID hit, or I just haven't found the MSCs for it yet.
To stick with airports/flying - the airport parking shops have been fantastic for me, and have saved me quite a bit of money in just a short period of time. Oddly enough, I had been already parking in the same garage for 1-2 years prior to finding out they were mystery shopped.
Other than that, the majority of shops I've done have been for lunch/dinners. Always a good time when you can get together with a friend, catch up on life, have great food, all the while being paid & then reimbursed your expenses. Also enjoyed a lot of the take-out, delivery and drive-thru shops over the past few months. Hope those don't go away now that restaurants are back to (near) normal capacity.