I've been looking into several flights that I want to book for next year. The routing seems very strict on nwa.com.

Example 1: I was trying to book a DAY-BOS roundtrip and the only option offered through DTW. On the way back, I would have wanted to fly through MSP, ideally BOS-MSP-DTW-DAY. I never get that option, even the options of having 50 flights displayed as opposed to 16.

Example 2: I was going to book 2 award round trip tickets: DAY-HNL for myself and DCA-HNL for my companion. It was extremely difficul to find common flights (ideally I was hoping we could meet in DTW and travel together from there). I would get totally different routings.

Is there a way to get different routings than those initially offered at nwa.com? Would it be worth to try calling or would I get the same result? Any suggestions that you may have are appreciated.

For option 2, have you gone the "search by schedule" route? If that fails, then you'll have to call the elite line and see what they can get worked out for you (of course, it'll cost you $15, but IMHO it's worth it). Try to route yourself via MSP on NW98/99 with the new A333.

First look up the routing rules within the fare rules. It may say that travel must only be via DTW. If not, then you will want to use the multi-city function and specify DAY-MSP, MSP-BOS. If it is a legal routing and there are seats in your booking class, nwa.com will price it out correctly.

The same should be basically true for the second example. Use Multi-city and search by schedule. If there are W or A seats you should be fine.

I've tried all sorts of searches and I never get the option to go through MSP. I've tried to make a multi-city trip but that ended up being considerably more expensive. The fare rules say:
4 TRANSFERS PERMITTED ONLINE ON ANY CARRIER - 2 IN EACH DIRECTION. NOTE - ALSO APPLIES TO NW AIRLINK FARE BREAK SURFACE SECTORS ARE NOT PERMITTED
I'm thinking it might have to do with the that. What exactly does that surface sectors thing mean?