I think the capping of all trips to one or two a roster would be the fairest way. The problem with capping the
unpopular trips or capping the
popular ones is what exactly is popular or unpopular? I have a friend who does nothing but JNB as her family lives there, and I also know some people who wouldnt want to do a HNL.
If you cap each trip to say two a roster (for bidding purposes), then everyone would be set to the same rule, the flying will be shared more evenly. If you put on top of that an electronic trip swap system, once the rosters are built then people can pick up or try to swap what they feel they do or dont want.
I would love to see the seniority bid system go, I think it is discrimination.
The simple fact of the matter is it would be too hard. You would have to get both unions' members to agree to it ( read: getting both divisions of the FAAA to actually
talk to each other

). With a joint seniority list, one division can't just drop the bid system, what would happen if you transferred division? where would you sit seniority wise?
Capping everything to two a roster and having instant trip swapping would be a simple thing to implement, and would make things much fairer for all