Between Disgaea 3, Ragnarok Odyssey, Persona 4 Golden (even though you said you usually don't care for turn-based but the game is still amazing and very big), Gravity Rush (it's an action game in an open world with RPG elements), Virtue's Last Reward, and Need for Speed already out, I'd say there is plenty for you to get you started.
Games coming out and should get a western release are Ys Celceta (game looks fabulous!), Soul Sacrafice, and I personally would add Legend of Heroes Zero no Kiseki at some point since Xseed seems to be determined to bring us those games.
Besides that, the Vita is a fantastic system. I love portables and I own every current portable out (DS Lite, PSP 3000, 3DSXL, and Vita). The Vita is by FAR the most capable and deserves to be owned by anyone who loves portable systems. The 5-inch OLED screen is mesmorizing. I highly recommend it. Although not selling all too well, the Vita will be fine. The PSP GO was just a less capable PSP and failed because people in general don't want DD only. --- If you want to see FF Type-0 localized, put it in your sig and go here to sign: http://www.gopetition.com/petitions/project-crystallis.html