PB Blaster and Kroil are the two best penetrating oils I've worked with. Both are aromatic. I know of nothing that doesn't smell and also works. A good cleaning and ventilation after the fact is the best answer I can come up with.
Another vote for ATF/Acetone. I'm rebuilding a couple of ~80 year old South Bend lathes and it was a real acid test for my battery of penetrating products (PB Blaster, Kroil, Liquid Wrench, etc). On the first lathe I tried them all and some worked some of the time but the ATF/Acetone mix often worked when nothing else would (e.g. seized taper pins). I used it exclusively on the second, more seized up lathe and it saved me tons of time and grief.
In the U.S. Navy we used to call it ' Panther Piss ', a concoction of Toluene & Naptha & Carbon Tetrachloride & Xylene - No Way Today the EPA would raid your place.
Sears and Roebucks had a great solvent called: Tirpolene thinner - It went the way of the EPA.
Goof-Off is good of somethings, as is Naval Jelly rust remover (Locktite). The smell dissipates overnight.
I've used Marvel Mystery Oil in the past to free the piston rings on my boat's diesel engine. Haven't tried soaking stuck bolts with it; not sure how great it would be as a penetrant, but I do find its wintergreen scent more pleasing than WD40 or PB Blaster.
PB Blaster's my go to for unfixing stuff. WD40 is good for displacing water, great penetrant, but I've always heard it's not the best lubricant.