Well, see above for thoughts. Chain, Repeat, Persist are also contenders. As are Silent and Empower.
Unfortunately Extend is a prereq for Persist, it's also not a bad choice for third level feat since you can use your second level slots to extend things like mage armour to all day sooner than you get the free cash to splash on a rod of lesser extend and long term buffs at level four without extend tend to crap out half way through the day.
Give them bread and circusses and the plebs wont rise against you. Give adventurers dungeons and trapped chests and they won't waste time looking to ransack your home and kill your wife.