Arbor Squirrelys around camp glory in coerthas were giving me decent sp, and the sp was actually pretty good when I duo'd with another conjurer my lvl. After a couple levels, the does become fair exp, and the wolfs are amazing sp in a duo. There is a spot, I think it's east of camp glory, that has several wolves all in the same area. A friend and I were getting 300-500 sp a kill on those things.
But the real sp is in partying at 20+. I have leveled since 20-29 in linkshell parties, and it goes great. Fast fights, 100-500 sp per kill, and it's a lot more fun. In an ideal party, we fly through mobs, destroying them 3 at a time when they link, and I get 300+ a kill from heals.
If you don't have anyone to party with, I'd suggest making some new friends or finding a decent linkshell... If it's time restraints that force you to solo grind, then Idk what to tell you, I guess just focus on leves or something. But if you are grinding for more than an hour at a time, you should definitely work on finding some mates to grind with. I haven't solo'd beyond leves since around 20 or so, and I don't plan on it anytime soon. So again, I strongly suggest going the multiplayer route.