Firstly, Agnew's resignation was wholly separate from Watergate, so he still resigns. Regardless of political capital, John Connally is a hard sell. Democrats see him as a turncoat. Republicans dislike him for being a former Democrat. And, to quote a problem he had trying to gain the Republican nomination in 1976, he saw problems as a Democrat but his solutions were those of a Republican.
Overall, Nixon basically wanted his second term to undue the "Liberal Nixon" works of his first term. Nixon hated things like the EPA and all the rest, and there is a myth of him as some secret liberal. In reality, these were the works of a lot of good government Republicans in the administration, and they embarrassed Nixon. With political capital, they would go away.
On the whole, Nixon also wanted to build the Republican party into a grand Conservative coalition that would dominate American politics as the Democratic party had since Roosevelt. He was inspired by Churchill in this regard, and wanted to make the Republicans a big tent of the working class, traditional Republicans, Southerners and anyone else he could get. I think Black Americans were included if he could win them. Basically anyone who was the so called "Silent Majority", and much of that did come to pass, although it was not as sweeping and dominating as Nixon would have tried for. Certainly it did not pass in the wake of Watergate, when the Democratic party rallied and the Republican party was weakened, and much of it did come under Reagan some years later.