While many here denigrate the multi-level lights like the L2D-CE/Q5, etc., I like them a lot because it is often when I just don't need the max level, and I enjoy the mega runtimes at lower levels while still being able to do what I want to do in the dark.
That said...
The most I think I'll ever need is the AE Xenide 25W at 1500 lumens. That's a "go to" light for when I have to answer a middle-of-the-night alarm call. I don't just want to see burglars, I want to blind them into submission.
Then for most other "long range" requirements, a Tiablo A9s (or 250 lumen variant) is about the most I need, because quite honestly, it can light up things that are too far away to see for me anyway.
For nice, bright "area" work, I think my new favorite is the MT-III. It's 600 lumens, but spread out nicely which makes it comfortable to see what I'm doing in a wide area rather than in a spot.
Beyone that, my smaller favorite is the L2D-CD/Q5 which is plenty bright for 90% of anything I really need a light for, but I especially like the low level settings. The low (12 lumen) setting is perfect for ambling around the house at night without blinding myself, and the medium setting (53 lumen) is more than I need for most backyard excursions.
So the direct answer to the original question of how many lumens I'm satisfied with, is: Probably 250 lumens is enough. As emitters become brighter in the future, I'd prefer that manufacturers pay a little more attention to designing reflectors that put any extra lumens in to better spill rather than trying to "out throw" each other with pencil thin beams.