I am personally in the any two weeks camp. The vast majority of pilots here don't want two consecutive weeks of vacation because it is pointless to have two consecutive weeks of vacation. If we started bidding for what we intended to actually use, these stupid shenanigans with bidding and trading to your cartel buddies or sugar daddies would stop and you would see a more equitable spread of vacation throughout the list.
I am all about seniority. The super senior should absolutely get the weeks of vacation they desire. They can do that, however, without block bidding 5 weeks of summer vacation that they will not use just to turn around and trade them out of seniority to their buddies. I once flew with a guy and watched him trade into a summer week for 5 buddy passes. Wtf? How is that any different than paying someone cash?