You can reach Bonn quite conveniently within about one hour from either Frankfurt (Main) airport (FRA), Cologne/Bonn airport (CGN), or Duesseldorf airport (DUS). Cologne/Bonn is the closest, so all other things being equal it is probably the best choice. From Duesseldorf and Frankfurt there are train connections to Bonn. Since to get from Frankfurt to Bonn, one should take a high speed train (InterCity or InterCity Express), this is relatively expensive. If you fly to Frankfurt, you should try to buy the train ticket to Bonn together with your flight (as a "connecting flight", so to say).
Please note that tickets for regional trains are not valid in ICE, IC and EC trains. For the latter, you need special (and more expensive tickets). The ticket vending machines show the available connections, and it's easiest if you buy a ticket for the exact connection you are going to use.See the local information page for more information on how to reach your hotel from Essen Main Station.
Phone +49 / (0) 228 / 98380-0
Fax: +49 / (0) 228 / 98380-11
Phone: +49 / (0) 228 / 22 58 68
Fax: +49 / (0) 228 / 24 15 44
Phone +49 / (0) 228 / 2691 0
Fax +49 / (0) 228 / 2610 70