travel sick
Been pricing fares to Michigan... so far, I'm impressed by NW airlines... they're the only website with non-stop, low fares and multiple-destination flight planning. I'm printing my results here for my own use:

From Seattle to Detroit:
1) 8:30 Dep. (NS) 3:24 Arr. #268
2) 9:00 Dep. (NS) 4:15 Arr. #276
3) 12:45 Dep. (NS) 7:57 Arr #278 ^

From Detroit to Portland:
4) 9:07 Dep. (NS) 10:57 Arr. #811
5) 3:30 Dep. (NS) 5:20 Arr #817

From Detroit to Eugene:
6) 12:10 Dep. (Sea) 5:10 Arr. #279/ 2225 (horizon)
7) 9:07 Dep (PDX) 3:22 Arr. #811/ 2275? (horizon)
8) 3:30 Dep (PDX) 9:44 Arr. #817/ ?? (horizon)

Price Combos:
(#1 or #2) + (#4 or #5)= $354
(#1 or #2) + #6= $476
(#1 or #2) + #7= $455 **
(#1 or #2) + #8= $401 *

Including Option for Traverse City:
Approx $533, Seattle to Traverse, Detroit to Eugene/ Portland
Probably don't want to do the reverse unless only coming to portland... too much flying + too many stopovers!

^: last minute option
*: best all-around fare
**: best for more time in MI