that really sucks I would be really pissed.
colotundra, first of all if I were you I would bring hell to that hotel for what happened, try to get a few nights for free
Ok that looks like some type of hard water, or water mixed with some type of contaminant, it is impossible to tell from a pic. If you were able to remove the stains from the glass I think you should be able to remove these stains from the paint.
You need to work on the stain as soon as possible,
those contaminants + hot sun could cause some damage on the clear coat (depending on what it is

)
If the clay bar did not work you need to try a polishing compound. Go to wal mart and buy
"Meguiar's Ultimate Compound", and some polishing applicator pads. This is perfectly safe by the way

, you can't damage yuor paint by hand unless you don't use the product correctly.
Follow this basic steps:
1) Park the vehicle in the shade (VERY IMPORTANT)
2) Wash area with soap and dry it.
3) With the surface cool to the touch, apply the "Ultimate Compound to the area" using the pad. Considering the pad is completely dry at first use "a nickel size amount of polish", you need to use enough polish to work the area.
4) Work in small sections for some time and apply pressure with at least 3 of your fingers in the pad (typically people tend to apply pressure with one finger, not too effective),
5) DO NOT let product dry, remove with a clean microfiber towel, multiple passes might be necessary.
6) After the stain is removed you need to apply some type of wax to the area.
Pls let us know if it works, don't be afraid of doing this IT'S OK
