Separating Senators and Representatives on the floors of the Senate and House by party has been a long-standing tradition that has done more harm than good by emphasizing, even creating, a wall between the political parties. Seating should be by state so that those who represent a particular state are constantly reminded who put them there and whose interests should be primary.
Why is this important?
Seating members of Congress by party only reinforces the bipartisanship that is crippling the effectiveness of Congress.