Thanks for all your thoughtful replies. This is a tough decision. Like you all, I have offers from other schools which include partial funding. But I think Michigan is the best curriculum for my needs (in particular, its quantitative focus). Another of my offers, Georgetown, may also be strong in that regard, but the cost of living in DC scares me!
I appreciate that there are non-university jobs available in Ann Arbor, but it's the benefits (part- or full-tuition waive, insurance) of a GSI position that make them so attractive. Unfortunately, with no funding and no savings (my wife is a first yr med student at Pitt - all of my current earnings are swallowed up there!), the remuneration from a non-university job would be a drop in the ocean (not that every little helps!).
One of my ex-colleagues started her MPP at Ford this academic year, and another colleague graduated from the Ford MPP last summer. The girl currently at Ford also received no aid for this academic year, and told me that they have sharply reduced awards in recent years (not that Ford is ever in the same league as some other programs!). My colleague who graduated from the program did get some funding. Initially she received a little, but she emailed and phoned Beth at admissions, attended the Open House, and they increased her funding a little. I think that may be the best strategy at this point. Now I need to decide whether to drop $300 for round-trip tickets to Detroit from the Bay Area!
Incidentally, my friend who began the program this year, without funding, is pushing to complete it in 3 semesters. That way, she will save an entire semester of tuition. May be worth considering, although I'm loathe to reduce my time at Michigan!