The classic response is that the only time deficit spending is agreeable is to tide over a depression. Of course, if you aren't already running a deficit, this is much easier to accomplish...

If you decide to infuse cash... the logical place is to invest in infrastructure. Replace some of that decaying infrastructure in the US.

Social programs are difficult to substantially cut, although they could be reordered/reformed.

Most everything else could be cut in principle. Obviously it's also possible to over-do it with short-sighted, fiscally irresponsible cuts.