Abaddon,
Yes, there are dozens of nude campgrounds/resorts in the United States. I of course tend to frequent all male resorts/campgrounds, but I run across information for mixed and family resorts when I do my research.
I prefer nude beaches to resorts. Beaches tend to be a mixture of all types of people, gay/straight, male/female, babies/grandparents. I think this is incredibly relaxing. No "cruise" mentality. There are always a few freaks. I think that is unavoidable. I've never been to a nude beach that was completely free of gawkers, but I just ignore them. My favorite nude beach is Haulover near Miami. Its wonderful and offers much easier access than the typical nude bathing areas which make you lug stuff down a mile of rocks or dirt road before you can take your clothes off.
Other favorite nude places include:
Mizo Beach near Madison Wisconsin. On an idyllic river setting and not real crowded. There is a boy scout and girl scout camp nearby there. When I was there several times during the day scout canoers came by and you could hear the troop leaders telling them to stay in the middle of the river, LOL, of course the boys were trying to get as near our shore as they could to check out the naked girlies. There is a picture of me at mizo beach on my Go West page.
Blacks Beach near San Diego. I've heard they may have closed this down partially or totally which would be a shame because it was an incredibly beautiful place to go naked.
Lake Travis near Austin Texas. Extremely hot in the summer because it is totally on rock cliffs with not much breeze. But the lake is beautiful.
Palm Springs has a number of nude resorts, gay and straight and I love Palm Springs.
Key West also has a lot of nude hotels/motels and I love Key West as well.
I think a Key West/Miami trip would be most fun for a European couple.
hugs
Joel