Hotel near Frankfurt airpot and easy activity for afternoon/eve in Frankfurt

There are two Marriott hotels actually in the Frankfurt airport. You can then walk to your gate.
Hope this helps,
Safe travels!

I would suggest staying in the Römer area, which gives you walking access to some great sights. Quick S ride to/from the airport. I stayed at Motel One Römer. It's part of a German chain that has simple but comfortable rooms and a really nice ground-floor common area. Good breakfast, too.

If in your budget, consider a private tour with Frankfurt on Foot. One of the owners -- Ms Jo -- frequents the forum (and recommends the hotel where I stayed). She gives a great, informative tour for a reasonable price. She met me at Motel One Römer. https://www.frankfurtonfoot.com/

I continue to say that Frankfurt is on the lower end of the tourism spectrum for a reason but if you have a couplea hours to kill, make your way over to the Sachsenhausen district, have a quick walk around, grab your place at a restaurant outdoor picnic table and order any dish that features Grüne Soße (Green Sauce) usually with hard-boiled eggs and boiled potatoes or if you're really hungry, order the Tafelspitz (boiled beef) mit Grüner Soße, maybe some Handkäse mit Musik (marinated Cheese with onions) and a glass of Apfelwein (Apple Cider) - there, you've captured the essence of the Hessen traditional culinary scene, you've paid your respects to Germany's financial capital and you're now free to move onward.

Save your energy for Berlin ... that's the treasure trove.

Thanks for the info on Marriot hotel. Would be great but it's $548 euros- probably because it's a Friday.

Motel One is in the neighborhood of 100 euro.

I can’t imagine a more informative, fun and worthwhile way to spend an unexpected day in Frankfurt than with Ms Jo or one of the excellent guides from Frankfurt on Foot. Highly recommend.

Thanks for all the great suggestions. We found a hotel near the airport and plan to spend time in the Old Center of town.

Sorry for that high price. There's also a Sheraton in the Frankfurt airport ( part of the Marriott group) and I've never paid more than 135 Euros a night.
Have a great trip.

What to see in Frankfurt:
* Kaiserdom
* Frankfurts new Alt Stadt
* Karmeliter Cloister
* Alte Nikolai
* Franconoford
* Römerberg
* Alte Oper
* Eschenheimer Turm
* Jewish Holocaust Remembrance Wall
* Medieval Jewish Cemetery on Batton Strasse
* Kleinmarkt Halle
* Teutonic Order of Knights Chuch
* Frankfurt Höchst and the Justinus Church, Schloss with dry moat, Farmers market on Tues. Fri. Sat. 07:00-13:00 (Höchst is part of the Half-timbered Route in Germany)
* Farmers markets on the Konstablerwache on Thur. and Sat. and the Schiller Str. on Fri.
* Bethmann Park in Bornheim
* Palmengarten (the butterfly house is supposed to re-open soon)
* Botanical Garden
* Main Cemetery - visit the American Kinderfeld, memorial site for 695 American babies of military families
* Goethe Turm in the Frankfurt City Forest
* Main Tower
* Städel Museum
* Schirn Museum
* Judengasse and Jewish Museum
* Film Museum
* Frankfurt Historic Museum
* Communication Museum
* Liebieg Haus Museum