I'm going to Frankfurt next month to try Sharks/Oase.  I'm staying at the hotel near the airport.

1.  I've read in previous threads that parking is not great late at night.  Should I not rent a car because of his reason?  Is parking an issue at Airport hotels?

2.   will public transportation will get me to my destinations with relative ease?

3.   what is a good option for mobile phone from Germany, since I don't want to pay ridiculous amounts and use my US mobile overseas?

Your input would be much appreciated!

First off, why are you staying near the airport?  Staying in Frankfurt near the main station or even in Darmstadt (for Sharks) itself would be a better option in my opinion.

I've never rented a car whenever I go to Germany.  Sharks is located near Darmstadt Nord (north) train station, maybe a 10 min walk.  It's easy to get to by train.  If staying near the airport and you want to take the train, you'll still need to transfer at Frankfurt HBF (main station) which is why a hotel near the main station would be better.  Alternately, there is a bus that runs regularly between the airport directly to Darmstadt main station and back.  I think it was $10USD one way when I took it a few months ago.  From there it's a short train ride to Darmstadt Nord or you can take a taxi.

It's been years since I've been to Oase, but when I went I took the train to the nearest station (don't remember which one) and from there it was a short taxi ride.  Others can reply regarding Oase, but based on my handful of visits to Sharks I couldn't imagine wanting to go anywhere else.

As far as cell phone, I'm not sure who you have, but if traveling overseas a lot T-mobile is a must.  Unlimited data and calls to the US are only 20 cents a minute.  

Hope this helps.

I was in Frankfurt in November and stayed at a 5 star hotel next to Frankfurt Train Station. It was exceedingly easy to walk across the street, get on a train to both Sharks and Oase and then take a ten minute cab ride to both places. Cost for cabs and trains was very reasonable. Both Oase and Sharks have train stations nearby that run back into Frankfurt as late as 1 am maybe later on the weekend. Frankfurt train station will also give you....in English....a train schedule to both FKKs respective train stations.  

As far as a phone, I used my US phone in Germany and texted while I was there. I have a well known US carrier. The calling option was expensive with my carrier 2.95 per minute. Texting was .05 to receive and .50 per text. I shut off my data while there...too expensive.

Alternately with my carrier, I could pull out the SIM card on my phone and buy a European SIM card at Frankfurt airport or train station that can be purchased on a per minute basis. The reason I didn't was I didn't need to make calls personally or use data independently. Virtually every place I went in Frankfurt had wifi and I simply used the location or hotel wifi for everyday data usage to include WhatsApp  

Hope that helps...

-- Modified on 1/19/2017 12:47:15 PM

Thank you gentleman!  Unfortunately, I should have ask before I booked a hotel at the airport, should have book one near main train station.  As they say, you live and learn.

Cheers!

I have stayed close to the airport and taken a rental car to Shark. Even though parking close to sharks do gets filled up there are more parking space half a block away.
I find rental convenient and comfortable mode of transport
There are plenty of parking close to the airport. Maybe getting to the specific parking is tedious as GPS is not that remarkable, but nevetheless it wasn't difficult

If one just want to hit Frankfurt area FKKs then public transportation would be more convenient imho.  All five major Frankfurt area houses are reasonably accessble via train/metro/tram plus short taxi rides from stations.  

Renting car itself is not too expensive in Germany however fuel price and hotel parking fee add up.  Car rental is more or less a must for Ruhr area FKKs since many are far apart and far from train stations.