It's now been nearly three weeks since I smelled any ethyl acetate or acetone. Those were the two last vapors I was exposed to in my former lab, as I cleaned out some dirty flasks, and those are two of the most common solvents that organic chemists breath in. Neither of them is particularly hard to deal with - acetone has a clear, penetrating solvent-y smell, and ethyl acetate, as a typically fruity ester, comes close to being pleasant. There's plenty worse out there. Hexane and methylene chloride are all over the place in a typical synthetic lab, too, and they're a bit less appealing with their flat paint-cleaner character. (They're rather less appealing from a toxicology standpoint too, for that matter).
Of the other common lab solvents, THF has a rather pungent ethereal smell - not something you'd line up for, by any means, and diethyl ether itself fills up your nose with great speed and thoroughness. Somehow, there's rarely a thin whiff of ether in the air - it's either nothing or a choking blanket of the stuff. Acetonitrile is something you'd think would have an interesting reek, but it defies expectations (and breeds doubt as to the broad-spectrum utility of the human nose) by having absolutely no smell at all.
Many of the really polar solvents have that feature. DMF has a smell to it, but it's surely traces of dimethylamine that account for most of it - in my experience, the pure stuff doesn't have much character at all. DMSO is the same way. There's something oddly scented there, and you can tell as it takes up olfactory room that you're not smelling regular air, but it's not as strong as you'd figure. As with DMF, you have to wonder how much is due to traces of impurities, such as reduced sulfur compounds, of which it wouldn't take much.
And the most pleasant of the bunch? Pure ethanol, for my money. It's not pleasure by association, either, because I don't really drink at all (and never have). But straight ethanol's combination of fruitiness and pungency is unique and appealing. Its cousins don't make the cut. Methanol's dim and harsh, and the propanols are no improvement: n-propanol (an uncommon solvent) is rather nasty, and isopropanol (the well-known rubbing alcohol smell) is not unpleasant, but rather strong, clinical, and somehow alien. n-Butanol, for its part, is quite foul in the manner of butyl compounds everywhere. Our noses have it in for straight four-carbon chains, and there's nothing to be done about it. Nope, it's ethanol, and it's not even close. Any other nominations?