Thanks to all the votes and comments. I took my warlock out for a spin and I have to say that while I'm completely n00b to it again and stand there trying to figure out what spell to cast or what to do when there are mobs beating on me, it was a lot of fun because I was grouped with others. Wichita's L34 Warlock, Baconstrip's L32 Enhancement Shammy, Rhubarb's L36 Feral Druid and my L33 Warlock were tearing up STV and that was a lot of fun.
Thinking about it afterwards, I have to say that my warlock synergizes (as Lou mentioned in his comments) with this group a lot better than I think a rogue would. A Shadow Priest would work but I'd have to powerlevel him to catch up and I just don't know that I'd enjoy it as much. With my lock (as compared to my druid), I have so many options now it's almost confusing.
Last night we were doing the Kurzon chain of quests in the north-eastern reaches of STV. The last step in the quest has you go into the caves where you need to take out Kurzon's guards and Kurzon himself, an elite. I think only Rhub's druid was the right level for the quest - the rest of us were under-level for it. However, we prevailed as a group even when the pull on Kurzon himself turned out quite messy. These mobs were orange to us and there were a lot of resists but no one panicked and we managed to get everything killed without any deaths (I think).
It was actually an interesting fight as Wich and I both used our succubi and tried to chain seduce 2 mobs. With the resists and adds we resorted to chain fearing mobs as well as trying to re-secude other ones and generally DoT and CC and survive. I ended up drain tanking a couple of the mobs for a while until Rhub could taunt them off me but this and the CC'ing provided enough buffer for our group to get the job done. This was so different from Wichita and my roles on our mains so it was neat. Normally he's dps/backup heal and I'm tank or dps and things like CC'ing are for others. In this case, neither of us could heal and our only options was to CC and DoT.
So, I think I'm sticking with the warlock for now. He synergizes well with our group. As it turns out there are quite a number of people with alts in their 30's so this group may get bigger than 5 people. This may lead to issues with grouping but we'll make it work. Most likely, not everyone will be on at the same time so hopefully we'll always have enough for a full group.
So far, it doesn't seem like any of us are in a rush to power level to 70 - which is good. Alts should be for fun and to reinvigorate us to play... maybe to discover something new. We don't need to speed these guys up to L70 to convolute our playtime and wonder who we should gear up and who we should raid with or PvP with. Right now, we'll just enjoy ourselves with old challenges, new dynamics and fun friends and experience the game from a new perspective.