I've heard really good things about the eRoll and Volt, both of which are mentioned here. I dumped a lot of money into a 510-style kid a couple years ago and just couldn't get into it, too much fiddling, batteries too weak, not enough vapor to really feel like you're smoking, which was more important to me than a device that made it look like I was smoking to other people.
Started again with a cheap eGo kit and Evod clearomizers, my smallest one sits about 4 1/2" high and is the size of a small cigar, and it works great. Got some backups of the same thing, tapered my use off the regular cigs for a week and quit completely almost a month ago.
Not sure what it is that bothers you about the size, whether it's other people's perception of you, how you think you'd feel using it, or the portability factor. I've got to tell you it's going to be a bit to get used to, but in the grand scheme of things carrying around 2 Egos (in case one tank runs out of juice or one battery dies) is a lot more convenient than a pack of smokes and a lighter.
This is a common ballpoint pen, the regular Ego battery and Evod that I'm vaping right now, and my smaller Ego battery, to show how small you can get if you want to. Whether or not you decide to start with an Ego or with a "cig-a-like" before upgrading to an Ego or an even bigger "mod" device (I'm perfectly happy with what I've got and plan to make it work for at least a few months), good luck!