In NRW pretty much all clubs are not FKK, only some small ones are. Many girls do walk around topless though.
For a whole day you'd still be best off in Living room I think, or Golden time, but that's quite a bit out of the way. You can also combine the two (same owners). Go to Golden time from opening till 6 or 7 pm and then go to Living room. If you mention this as you're leaving GT, you get a 25 euro reduction card for the entry fee at living room.
Samya can get fun, but there really is no point in being there before 6pm... and even then in only start to be fun around 10.
All of these clubs are quite a bit smaller than Sharks, but (depending on the day) Samya, LR and GT will al have 50 or 60 girls there at the least (some days many more). Golden time will have a few less, probably the least like the clubs you have been to before.
Note that Oceans and Magnum are actually two of the largest clubs, but for me personally not really worth it (and only fun at night).
PS the pascha thing isn't really that special, there are laufhauses and eros centers all over Germany. The biggest areas like that are in Duisburg and Frankfurt. Be prepared to climb lots of stairs.