I completely agree with you regarding museums holding large collections which they do not exhibit; in fact, I think it highlights how a sort of 'George-ish' tax

I completely agree with you regarding museums holding large collections which they do not exhibit; in fact, I think it highlights how a sort of 'George-ish' tax on paintings might be helpful! With respect to your second point, I think that taking each out of circulation has different effects. I would guess that most assets have a value of about what they're worth (i.e. the price mechanism works). I think Georgism is at least a valuable paradigm, and would be in favour of at least some pseudo-Georgist measures, such as only taxing land, to encourage higher-value uses rather than land+structures, and taxing all sorts of land at the same rate.