Westend is very beautiful. Many turn of the century houses and villas. You might take a look at this hotel:
http://www.hotel-goelz.de/

Or this one:
http://www.arthotel-frankfurt.de/das_hotel.htm

The Palmengarten is always lovely, plus they are having open air concerts there all summer, Jazz, Blues, World Music. Nearby is also Grüneburg Park. Take a walk through there and you will discover not only a Korean Temple and garden but also a beautiful Greek Orthodox church set along the side of the park.

We are booked at Hotel Goelz and it looks great. Thanks so much.