In General
 Proper Role
Government's legitimate role extends at least to the following:
- protecting the weak from the powerful
- providing that which can be provided by neither individuals nor private organizations
I don't think it has any business in anyone's bedroom, except to the extent that bedroom activities are either (a) non-consensual or (b) a potential danger to those outside the bedroom. I have yet to hear any defensible examples of (b), so government's role in the bedroom is limited to (a).
To the extent that people are engaged in business with significant profits or where other people's welfare (e.g. employees, community, etc.) is involved, then yes, government does have an interest in "people's private business". I'd like to see a substantial gap between where profit starts and where government gets involved on that basis, however. If you have employees, though, government has a role in protecting them from you (and vice-versa).
 "Small Government"
- While there is certainly a lot of bloat an inefficiency in most governments, you can't just get rid of that by reducing government revenues.
- While government can be oppressive, cutting government revenues will not get rid of that either. It will just reduce the quality of service, leading to more oppressiveness (because oppression is cheaper to provide than fairness).
- /prostitution metaphor: government is a pimp, and we are the hookers
 United States
 The Constitution
- The founding fathers had a design goal with regard to US government.
- The expression of that design goal is primarily in the form of the Constitution. (Supplementary documentation includes the Declaration of Indepenence, the Federalist Papers, private letters, and so forth.)
- The design goals included personal liberty for all stakeholders
- That particular design goal is no longer being met.?
(Originally posted here as a comment; access limited, unfortunately.)
 Federal budget
Off the top of my head, here's how I would classify a few federal programs:
 unnecessary; kill them
- foreign wars
- overseas military bases
- fossil fuel subsidies
- domestic spying, especially warrantless
 of dubious value; re-examine carefully
- farm subsidies (especially for large operations)
- CIA needs to be cleaned out and downsized
- FBI: useful core, but lots of corruption
 necessary, but implementation may be suboptimal
- Medicaid / Medicare / Social Security
- scientific research
- NASA / space exploration
- environmental regulatory agencies (EPA & others)
- safety regulatory agencies
- FCC (needs to be de-coupled from industry influence)
- USPS (would currently be profitable if not for new retirement funding requirements)
 expansion of service needed
In general, social support systems need to be expanded -- mostly because of jobsolescence. I support the idea of finding non-governmental ways of providing these services, but those alternative methods must be reliable (I do not consider present government programs to meet this qualification).
It has been suggested that if government were to simply back off in this sector, private charity would "take up the slack"; I think history shows this not to be the case. There would be a significant uptick in private charitable contributions, but it wouldn't come anywhere near making up for the loss of existing government programs (as pathetic and patchy as they are). We would essentially be recreating Victorian London -- and anyone who finds that a pleasant prospect needs their head examined.
A few specific services that need to be expanded:
- healthcare, especially preventive medicine
- mental healthcare -- everything from voluntary outpatient to involuntary institutional
- everyone needs to have a minimum living wage and adequate housing
- education -- especially K-12
- ...and it needs to be understood that creationism is fiction
- environmental and safety monitoring and data-gathering
- enforcement of anti-pollution and safety rules
- informational compilations and data feeds of all types (environmental, socioeconomic, financial, science...)