The best thing for party seeking is free advertisement for it by having a party seeking flag appear by your name like in 11. That way others will subconsiously also know to seek a party.

In the new search:
There should be more tabs (that you can flick back and forth through like the tabs in your Inventory) that are titled "XP PARTY" "DUNGEON" "SYNTHESIS" Etc etc, allow people to list themselves under more than one category at a time. It would help clean up the search categories too once a lot of people start using it.


For the old method:
I think the old method should be merged into the new method, because still even if we can flag for parties, there are still going to be people shouting for things like dungeon or NM runs, as in 11 people would shout in whitegate/jeuno. In that regard, I wouldn't mind a widget/gadget/message type thing that announced when parties are being formed, something like
"CHARACTER X IS SEEKING MEMBERS (25)-(30) TO CLEAR THE THOUSAND MAWS OF TOTO-RAK"
"CHARACTER Y IS SEEKING MEMBERS (50)-(50) TO BEST THE FACTION NM TARBH UISGE"
It would be an alternative to a spam fest global chat channel.

Or even just another tab in the new search UI labelled "OPEN EXISTING PARTIES" that let a party leader recruit with a stated reason.