Yeah, I'm collecting Pure Seeds for Temporal Tower. Can't go wrong with 'em!
As for the Monster Houses, I have a certain tactic.
First off, I get overlevelled. I do tons of extra missions, set myself a target of what level to reach before I do the next story mission, and just grind like crazy.
Then, I make sure to have the following in my bag for each dungeon (not the ones with bosses in the end, mind. I have extra for those): At least 4 Reviver Seeds, at least 2 Petrify/Foe-hold Orbs, At least 4 Oran Berries, at least 2 Max Elixirs.
Then it's just a case of getting into the Monster House, petrifying them all and taking them out one by one.
SUCCESS! And a whole bunch of Gummies and experience as a reward!
Never fails! Never fails!*
(*cannot guarentee that this will not fail)