As I mentioned previously, my goal in DDO was to see how far I could get solo without repeating content. As of last night, I have concluded that it's around level six and three bubbles. I could have maybe squeaked out some more levels by banging my head on level 7 content, but that's kind of a losing proposition because I'd have to start in on level 8 and 9 content with fewer abilities to get through level 7.
I have done all the free quests I could find wandering around, and bought nearly every adventure pack with content for level six and lower. One area that I messed up was not getting anal enough about doing wilderness deeds earlier. For example, I would leave most wilderness areas long before I had even reached 400 kills, which is leaving a lot of XP behind. I also didn't start getting really anal about exploration points until level four or so. I imagine I might have been able to make it as far as 7 or 8 if I had planned better.
Still, it's not as if I don't have a ton of things to do. The loot that you get doing certain quest chains varies pretty wildy from one run to the next, and so it's fun repeating them just to see what rewards you get offered. I'm also not having to repeat a lot in the first place. When I got stuck at level six, I went back and gunned through an old five quest chain twice, and viola I was seven and change.
So far I have been able to get by on my Paladin using zero hirelings completely solo. There have only been a few quests I couldn't get through if I was doing them at the correct level, and those were mainly quests hardwired to require a group. For example, in one quest four switches have to be activated at the same time in different parts of an instance.
I have to say rumors of DDO nearly requiring a party seem to be exaggerated. There hasn't been a ton I couldn't do solo. Though, admittedly, this is on a 'toon designed to be a low level solo powerhouse. I imagine a greater proportion of content will lock me out at higher levels, but so far my options don't seem nearly as limited and repetitive as I had feared. The one caveat is that I needed to buy adventure packs, the free content is quite limited from level four on.