In the opinion of the submitter still the best hotel for spotting at Frankfurt. The Intercity is a 10 min walk to the spotting area at the end of the runway.
If you ask for a room looking over the airport they will charge you 10 euro per night extra so well worth it if the weather turns bad and you need to stay inside. Food and drink is good while the breakfast is a bit on the expensive side there is a very good choice. They do have a shuttle bus which they charge for, but the public transport bus stops right outside the hotel and costs 2 euro back to the airport.
