Everyone interested in political parties should read recent posts by Hans Noel and Greg Koger about what parties "really" want. Should we think of parties as ultimately interested in seeking and winning office? Or in ultimately controlling public policy?
I have a dog in this fight. I think both sides are (partially) wrong.
It's a mistake, in my view, to think of parties in such a way that they must ultimately be defined one way or another. It misses part of the essential nature of political parties, which is that they are open-ended: parties are creatures of their members, and of their political context (which includes such things as the rules of the political system, but also perhaps political culture), and therefore different parties at different times are interested in different things. Some will be driven by office; some by policy; some by organizational maintenance; some by profit.
For any given party, we can look at which of these motives tends to predominate. It's probably the case that we can generalize some, too. Within parties, politicians and others whose jobs depend on office will tend to be driven more by the election motive. Party-aligned interest groups and "amateur" activists will tend to be driven more by policy. Those within formal party organizations (the DNC, the NRCC) will tend to be motivated by institutional maintenance -- like government bureaucrats, they'll care more about maintaining their departmental and organizational budgets, and try to insulate themselves from either electoral defeat or public policy. The current US case is unusual comparatively and historically as far as I know, but it ads another potential group and motive. When party professionals are organized outside of formal organizations and become for-profit entrepreneurs (true of campaign consultants in US now; also presumably true of, say, Fox News), then the profit motive is involved, as well.
On the other hand, generalizations only take us so far. We think of politicians as motivated primarily by office, but Aldrich and others show that policy can really matter to them. In some situations, profit may as well; think of presidential candidates running for a Fox or MSNBC contract. Party-aligned interest groups may be in it for the policy...but it's not unheard of for organizational maintenance to be important within lobbying shops or PACs. For any particular party or party component, motivation is an empirical question -- and one that's hard to get at.
But putting that complication aside, part of the job of party students is to assess the factors which will make these various groups become more or less important within parties. What we know going in, however, is that parties differ, considerably, on which of these is more important -- and therefore we should expect "ultimate" party motivations to differ, as well. So no single study is going to tell us what "parties" or "politicians" or "interest groups" want, because we should expect all of those to differ over time and polity based on different political contexts.
Party scholars, too, could research the troubles associated with different parties as different motivations dominate, both in terms of the health of the polity and for democracy. So for example excessively bureaucratic parties may be problematic for democracy because they may be impermeable to anyone outside of the formal organization. Or, parties dominated by the profit motive may be dangerous if they wind up having incentives to lose elections.
I'm open, too, to other potential motives.
At any rate: I do think that this is the best way to think about parties, and that a lot of useful work could be done filling out the relationships I'm talking about here. I don't think we've done much of that within American party studies, and to the extent I'm aware of it (some, not nearly enough) the same holds true in comparative parties.