Well, fire/thorns should have a fair number of AoE's, and should function well in the thick of things. Electric gives you buildup for damage, but it's a pretty blappy set. Energy should have plenty of stuns to stack with flashfire. (Your primary mitigation.)
Thank you Seldom.
I may give Fire/Energy a try, just to see how the extra bit of soft control from Energy's KB and stuns works out.
Word to the wise: Fire's immobilizes remove knockback. On the plus side, this lets you immobilize a group, put a bonfire under them, and get some okay damage that way. (Renewing the immobilize often to prevent scatter.) On the downside, if you throw out your immobilize, none of your energy blasts will knock them off of their feet for the first bits of the immobilizaes' duration. Not good/bad, just so you know. Oh, and /Energy is probably one of the earliest blooming sets, so you have that going for you.
Understood completely.
My plan was to hold off on the immobs until later, and use Char plus lots of KB as my mitigation at the lower levels. Then later, when I have enough slots (and Hasten) to get my soft controls up pretty much every spawn, I can take the immobs. I've used a similar strategy before with other Doms and it worked out pretty well.
Also, this toon probably won't be doing huge amounts of soloing. I have two RL friends I run with almost every night after work. So making sure I'm 100% safe at the lower levels won't completely fall on my shoulders. 
Thanks again for your input. Now the only bad thing is I've also had an idea for a name I really like for the fire/thorn set combination. Hmm, I may have to make up two Doms.
Last night I was thinking about the only two Dom primary sets I haven't tried yet: Fire and Gravity. Since I don't have the strength of will to go with Gravity right now, I decided on Fire as the primary.
But which secondary to go with eludes me. I'd also like to use one of the secondaries I haven't gone with before. Those are: Thorns, Electric, and Energy. I have concepts for all three, but just can't seem to make up my mind.
So I ask you my fellow Doms: of those three sets, which would you pair with Fire? And why? In looking at the sets I'm not noticing any special synergies, but I may be overlooking something.