The best place to watch CN and CSX is at Trowbridge. If you want to watch NS run by, I would suggest Michigan Ave. in downtown Lansing.
Anyway, CSX can and will run anywhere from 6-10 trains a day. The best time to see CSX stuff is in the Afternoon and Evening.
Here's a few CSX trains you might see:
Q326: Chicago-Detroit -Usually runs in the afternoon or evening
Q327: Detroit-Chicago -Usually runs in the late afternoon or evening
Q335: Toledo-Grand Rapids -Usually runs in the afternoon (any time, but recently has been between 2-4 PM) but some times will run in the late morning
Q334: Grand Rapids-Toledo -Unless you are coming out in the middle of the night, don't expect to see this train
X500: CP Runthrough train-Chicago-Detroit -Times vary for X500, but it usually passes by in the morning
Coal, Coke, Grain, and Lime extras are also possible, and CSX will usually run at least one extra a day, sometimes two or more.
As far as NS goes, they only have one train up here, B30.
B30 runs from the Saginaw Yard (on Lansing's northwest side) to Jackson. They start out in the morning, and can usually leave at anytime, between the late morning, and late afternoon.
Having a scanner will really help you for CSX and NS in this area.
Hope this helps.
