Translating the graph in hesk's link:
Which coalition would be best for Germany?
Within the CDU and CSU:
Within the Greens:
Within the Left Party:
Also, I fear, that the SPD doesn't really appreciate the Greens, although it was the strong showing of the Greens in 2002, that enabled them to continue the coalition then.
Same with the Greens, but your interpretation sounds plausible, too.
The problem is inherent in the poll. First, the question can be interpreted in two ways:
SPD voters favor a grand colaition because they see this, rightly or wrongly, as the only way to stay in pwoer.
CDU voters would see it as a failure in the election.
Same thing for the small parties, who don't want to be left out (although some there probably take the strategic view that a grand coalition can only favor those outside, i.e. them, at the next election) In the long run, we're all dead. John Maynard Keynes