Americans ought to look at what other countries do, though that does not mean slavishly imitating them. One thing that we don't need is a monarchy, for instance, even a mostly ceremonial one like in the UK, Netherlands, Denmark, Norway, Sweden, Spain, or Japan.
Looking at quality-of-democracy indices like the Economist Democracy Index, Freedom House's Freedom in the World, the Democracy Index, the Fragile States Index, etc. one finds that several countries score consistently better than the US. Looking at their governance, one finds these features:
- A parliamentary system: most or all of the executive branch is run out of the legislative branch
- Proportional representation
- Only one legislative chamber, a unicameral system, or else a bicameral system one dominant chamber
- A separate executive is weak and sometimes absent
The US fails in all four aspects.
The Economist Democracy Index and
List of countries by system of government and
List of electoral systems by country
In the EDI, the US currently scores 7.85 ouf ot 10, at #30.
Proportional representation is used by most of the higher scorers, with exceptions like the UK, Canada, and Australia having all single-member districts in their lower houses.
A parliamentary system is likewise used by most of the higher scorers, with the US beaten by these countries with a strong independent President: Uruguay, Costa Rica, and Chile. Some countries have a hybrid or semi-presidential system, and these ones beat the US: Taiwan, France, Portugal.
I can't find much on the relative powers of the two chambers in bicameral systems, though such upper houses as the Canadian Senate, the UK's House of Lords, and Germany's Bundesrat have relatively limited powers. Australia's Senate seems to be intermediate between those and the US Senate.