Nice thread -
There are lots of costume items I'd love to be able to wear on a day-to-day basis. Well maybe not quite day-to day...
1) Full blown Napoleonic-era military uniform. Something like the British Rifle "greenjacket" uniform or maybe the French Chasseurs, complete with pelisse.
2) Cavalier oufit, with hat and rapier! Love all the frills.
3) Cape, definitely second/third this suggestion. How cool would it be walking down the street, cape swirling around you.
Seriously odd choices I know!
At times I've also thought about a modern twist on a frock coat. I think it could be pulled off - just above knee length, very flared skirt, lots of waist suppression, hacking pockets, peak lapels, probably either single button or maybe 2 button. In black, indigo or even a forest green. Complete the look with dark trousers and black shoes or white breeches/black riding boots, white rose boutonniere (or maybe an orchid?) and a white ruffled shirt. Either no tie or a white cravat.
Insane? Yeah, probably! But worth a second look, I think you'd agree!