I like to prepare before delving into massive games. So I hear the games are long, but how long?

40 to 50 hours for a newcomer.

Once you know how the games work, 30 hours is how long it takes me. Its not that they are very long, they just have a lot packed into the game. You can sift through the bs and pick a side to go with. Do all their quests, getting more powerful, and thus finding out about new things. That makes it easier i think. Pick a side, find whether their beliefs make sense, which is the lesser of 2 or even 3 evils.

I logged 42 hours on Geneforge 1. That includes an hour or two of replaying from an older save for a different ending.

I think about 50 hours for each game if you try to complete each area. Probably more like 30 if you just do what is necessary to beat the games with a decent ending. Not sure though, I have a tendency to take my time and each game though took me about 50 hours.

Avadon was supposed to be between 30 and 60 hours.
It took me 90!
I guess I have 400 or so hours of gameplay ahead of me then.