Some suggestions for dealing with the problem of your end columns cracking or leaning if you use the 180 foot long beam solution:
1) The end columns could be brought in, say make the end spans 50 ft with a 10 ft cantilever, possibly tapered. That would help in a number of ways.
2) If you leave the columns at the end, make the end columns less stiff in that direction by using rectangular columns. Would not help the lean, but may prevent cracking.
3) Allow the floor to shorten before the floor to column connection is made. You could use sleeves over the vertical bars, force the beam to slide on the column, then grout the dowel bars.
By the way, the advice attributed to Aalami to model the bottom of the exterior columns as pinned really doesn't help with your problem. May be OK to model it that way, but if it actually works as a pin, that would just shift the cracking of the column to the inside rather than the outside.