I feel quite sure this is covered within all the comments, but lack of time dictates that I post a query for a good but moderately priced hotel very near to Frankfurt In't. Airport. Come in at noon on one day out early in the a.m. the next.....Courtesy van to and from, a definite "plus" - Thanks for suggestions!
The thing is, is that moderately priced hotels are not really "near" the airport. You will spend lots of time waiting on your shuttle or courtesy van, when in less time you could have taken the train into Frankfurt in 11-15 minutes. These S-bahns run every 20 min.
What time is your flight? What is your budget. Moderate prices are different for different people.
Depending on when you will be here, you can get a very nice double room for 75 € or less, in many of the hotels in the city center of Frankfurt.
There are plenty of posts on here with hotel suggestions.