However, I do think there are some districts/states where a more conservative Democrat would fit the constituency poorly; e.g, I endorsed Hirono in HI because Case would have been too conservative, IMO.
This makes zero sense. If you are willing to prefer "conservative" Democrats in districts in which Republicans are a "better fit," then out of consistency you ought prefer "conservative" Democrats in districts in which "liberal" Democrats are a "better fit."
Frankly, if you really are a "conservative Democrat" then you ought to aspire to the day that the Democratic Senate caucus votes out a Harry Reid in favor of a Ben Nelson. Preferring a Hirono over a Case in a Democratic primary completely sabotages that goal. Majorities are built by winning tough districts, not just ones in which your candidate is a "good fit." That's your ultimate goal, right?
Frankly, I don't see the "conservatism" of a Case in any way being a detriment to running against Lingle. Frankly, Lingle's best hope is the Democrats nominating someone to the left of the electorate. Moreover, primaries exist for people to vote their differences. I would fully expect "conservative" Democrats in Hawaii to naturally gravitate to Case, and "liberal" Democrats in Hawaii to naturally gravitate to Hirono.
It makes zero sense because you are a modern right-wing partisan. There are numerous differences between the Democratic and Republican Parties that transcend simple policy debates, and one of them is how each party views its constituencies as a whole.
Democrats - liberal, conservative and moderate alike - understand and mostly appreciate the diversity of our party and its ideas. We truly are a big tent party and it is how we have survived in an era in which had we been as ideologically pure as the Republican Party is today, we would have been decimated. Much like the Republican Party will be over the next 10-15 years.
Republicans - conservatives and only conservatives - now view any differentiation between their individual ideology and that of others as malignant. The ideological purification of the Republican Party has mostly completed itself in mainstream Republican circles and the House of Representatives, and will most likely be finished after these elections in the Senate.
The breakdown of the Republican Party and its individuals - namely people such as yourself - to understand the necessity for variation in ideas in order to be a successful governing entity is the reason the political system is broken today.
In the past, each party had to debate within itself before heading to the floors of Congress to debate one another. That's why and how compromise worked and it was how things were accomplished. The Democratic and Republican coalitions of the past that were united by seemingly odd (in today's sense) factors have shifted into a bland, predictable entrenchment of similar ideologies. The Democratic Party, however, hasn't engaged in ideological purification to the same standard and I can speak for the uber-vast majority of Democrats in saying that
we appreciate our Claire McClaskills, Jon Testers and Bill Nelsons in addition to our Bernie Sanders, Sherrod Browns and Chuck Schumers. 
