As I'm sure you know, I think the Senate had 3 main differences from the House:
1) Representation of the states...the spread effect you mention. This is the weakest of the three, I think.
2) 6 year terms (to purposefully make the Senate less susceptible to trends and hot issues...to lessen the ability of government to respond quickly...to slow things down until cooler heads prevail)
3) Senators selected by the states, not the people. This was the strongest (and most pro-Federalism) of the three, but it was abolished by the 17th Amendment.
The 60 vote rule is another difference...enacted by the Senate. The 60 vote rule slows things down just like the 6 year rule, perhaps even better. But, it is just a rule of the Senate, and as such, it can be taken out by 51 votes, judicial nominee or otherwise. Chris implies that the Reid Option (setting aside 60 votes in favor of a simple majority) is limited to judicial nominees, but that is only because Reid made that exception. The GOP can sit tight and honor Reid's decision...until another Dem comes along and finds another exception for something important to them. Or, the GOP can make its own exceptions like Reid did. Their choice.