Scientific analysis has been done on this subject, and it's somewhat at odds with the conventional wisdom. The conventional wisdom is the fast guy bats first, the best hitter bats 3rd, and the second best slugger bats 4th.
Actually the most important spots are 1,2, and 4. 4 is much more important than 3, because they often will either lead off an inning or bat with someone on base. 3 often bats with 2 outs and nobody on base, a largely useless situation.
The leadoff hitter actually doesn't need to steal that much, because the big hitters are coming up after. Stealing is for the bottom of the order when you are trying to manufacture. It doesn't really matter since the cubs don't steal.
1: Fukudome high obp guys when used correctly.
2: Should be Soto, but because he's catcher, which takes a lot of work, I'm moving him lower. So I'll put Starlin Castro here.
3: Carlos Pena, Homers are still useful in the 3 hole, and he's high OBP so I'll keep him up here.
4: Aramis Ramirez, best overall hitter with power
6: Soriano, his homers should be productive after Soto's high OBPs
7: Marlon Byrd, batting after Soriano should cut down on double plays.
8: Darwin Barney/Dewitt, Barney's showing good promise but I still have to put him last.
I'm leaving Baker off this list because he should really be traded if the Cubs want to go with Barney. Dewitt should see action against certain righties that use a lot of sinkers and sliders or if Barney cools off. I'm not sure on 5-7 spots. They are all pretty good hitters and a bit hard to predict.
This optimized lineup strategy is published in quite a few places throughout the internet. I've seen it multiple times on fangraphs.com. The main takaway message is the best hitters go at 1,2,4 then 5th then 3rd.