If you can find 91% isopropyl it works better than the 70%. Some pharmacies sell 99% and that works great. I haven't used a pure denatured ethanol, but I'm sure it'll work as advertised above.
My experience (mostly UCLs and camera filters if they've gotten really gunky) is that alcohol is not going to hurt most coated glass. I'd be a little wary using it on plastics without testing it on a particular sample... Note you do have to be careful of the alcohol dissolving the glue that binds the glass to the threaded rings for filters and the body of a camera lens, etc.
I have installed and cleaned lenses in various things and for that I use a trick I read about in an article about opening and working on hard disk drives at home. Apparently you can temporarily strip most of the dust out of the air in a bathroom by running the shower on hot for few minutes until a bunch of steam is formed, turning the water off and waiting several more minutes for the droplets of water to settle-out. Supposedly the air in the room after this is remarkably dust-free. (I'd be interested to know how much difference this makes quantitatively...)
The few Mag's with UCLs I've done in this sort of environment do seem to have have very little residual dust in them. I clean the lenses wearing power-free nitrile gloves, using some strong isopropyl alcohol and soft cotton cloths (e.g. freshly washed undershirts, no fabric softeners). Wash your gloved hands with the alcohol to remove any residual oils before starting. After cleaning the lens, carefully use a blower to get any cotton lint off the lens before assembly...