Visited two FKKs in Frankfurt, Manhattan http://www.fkk-mainhattan.de/english/index2_gb.html & Oase http://www.fkk-oase.de/FKK-Oase?Sprache=EN .  Talk about each below and present my comparison; this was my first FKK experience, my visit to Manhattan was on a Saturday at opening 11:00 through 10:00 PM, with a two hour break.  My visit to Oase was Sunday from 1:00 in the afternoon until 10:00.  I’m a non-smoker (seems to be a minority there)

Locker rooms
Manhattan has two, assignments spread out as guests check in.
Oase single locker room, lockers are assigned sequentially.  Resulting in means group of guys are cramped together all trying to get their clothes off & stored in a consolidated area.

Smoking (I’m a non-smoker)
Manhattan had a room assigned for smoking
Oase only seen one nonsmoking sign

Toilets
Manhattan had a couple spread out
Oase had 2 pissers & 2 shitters next to locker/changing room downstairs, & singe out on the lawn area behind the outside bar

Food
Manhattan had a buffet style breakfast spread, with eggs, hardboiled, fried & scrambled, several hot and cold meat selections, rolls, cereal, coffee (really good coffee) espresso machine, milk etc.  Lunch they fire up the grill outside, fresh hot food, dinner nice selection of meats and vegetable was always well stocked.

Oase (for Breakfast/lunch) has all food behind the bar.  Believe to have discovered where Seinfeld received inspiration for the soup dude (don't want to unintentionally offend anyone)  she was a bitch, plain and simple I politely asked for a croissant, marmalade and a water, got the croissant and some butter, she then went onto next customer, he gave his order & reminded her I had requested marmalade & water, got a sour look from her she gave me two marmalades and moved onto next couple customers, when those were gone & I was still standing there she gave me a what ta fuck look I said water.  I mean after all it is her job maybe they should re-assigner her to toilet bowl cleaning, there are only three so her job would be a whole bunch easier.  Now the gal at the outside bar, was so nice, what a stark contrast.    Only problem was you only get drinks outside, need to go inside for food, I avoided inside bar all together I mean I'm a paying customer why should I have to deal with her shit.  Now at 19:00 they have an outside BBQ that has a good spread of chow & you don’t have to deal with the indoor bitch..

Girls
Quantity, quality, variety I would say was the same across both clubs, bit sparse at Manhattan first thing (course I was there much earlier than Oase) the girls there mentioned it was very unusual to have so few girls first thing, they usually have at least a dozen, selection picked up quickly and after all I’m on no hurry.. If you can't find something in these crowds that gets your dick hard you need to see a Dr. & I mean right now. All varieties of titties from A to FF, pink nipples, puffy nipples, perky and slightly sagging, body styles from thin waifs to bit O’ meat on the bones, majority of kitties were shaved clean, only spotted one or two with small trimmed patch, light skin, dark skin, tan lines, no tan lines, all, minus sexy high heels, were naked, damn getting hard again just remembering the sights….

Sauna and steam bath
Both bout equal, though I think Oase is hotter, plus they have a second sauna room.

Whirlpool tubs
Oase is larger and has industrial size pumps, great pressure from the jets.
Manhattan had home style model which was smaller.

Showers
Both about equal

Accessibility (If you’re driving rental car no real delta) however for public transport:
Manhattan easy tram 11 or 12 ride & short walk
S bahn train & taxi bout €10 each way

Beer & booze
Manhattan free beer on tap - pay for bottles & liquor
Oase pay for bottle beer $€10 each pay for liquor

Re-entry
I know you can leave & return to Manhattan as I did with no issues, not sure bout Oase, course Oase is in the middle of farm country a €10 taxi ride each way for access to anything close to small suburban life.

Masseur
Manhattan set a 19:00 appointment, at 18:45 Daniel, masseur came out from previous client, noted to him I was on list as next guy, informed me he would be ready at 19:00 just needed to get things ready.  Was a great massage, highly recommended..  Room is isolated from rest of the club, heavy sound proof insulation on the door really tranquil environment, soothing background music, very relaxing environment.  

Oase made my desires known to masseur at 18:00, she told me next opening was for 19:15, was uncertain if I wanted to wait, but thought yeah spoil myself.  This room is just off the indoor large Jacuzzi tub, and has a glass door, I would imagine is not the best for sound isolation  Got outside her booth at 19:00, figured she required a bit of prep time like Daniel.  She was working on someone & I had no desire to interrupt, so waited outside the door.   Then a guy walks in and sits in a chair inside her room, must have been friends with the guy getting the massage as they all started talking, then the guy laying down gets up & this new guy lays down, figure OK maybe she struck a half & half deal with them, nope when 19:15 rolled around she kept on working on the new guy, I walked up to the glass door and got the shrugged shoulders thing.  Not so professional.   Yeah maybe I should have waited however when I initially spoke to her she earlier she was waiting on a client who had an appointment and wanted to honor his time, guess the concept of appointment is only understood sometimes.

Given my two day experience I have no clue why one would want to go to Oase when Manhattan offers same & better service at a much more convenient location, and friendlier staff.  Yes I'll send a note to Oase annotating my experiences, should they care.