The Riva 510 or the eGo seem to be the most common next steps for Blu users. It has an extended battery life and tons of options for low-res atties and cartos for more vapor. Check out the vendors section in the forum. Most of them carry these models and you should be able to get a starter kit for around $45.
I concur on the Ego as your next step as a vaper. It was my second PV, and over a year later and 6 or 7 PV's later, the Ego is still the one I keep going back to. If you still want the ease of having filled cartos, try the Fluxomizers at GotVapes. They're easy to fill and the true flavor of the
juice comes through...with tons of vapor.
You aren't going to find a battery that's the size of a cigarette that has longer life, unfortunately. The Ego will allow you to vape all day without having to worry about charging constantly, and while it's larger than the Blu or similar models, it's still reminiscent of a cigarette...sort of. Soon, you won't even care that it's not the size of a cigarette. I promise.
As for smooth flavor, I've tried a lot of liquids and I have to say that Virgin Vapor has the smoothest, cleanest, best liquids. And they're also perfect for a new user because they won't gunk up your equipment (which is, in my opinion, one of the biggest stumbling blocks for new vapers).
Hope this helps.
