Odeonsplatz is one of the best areas. You'll find yourself in the heart of Munich and it doesn't matter if you want to visit the old town, go shopping, look at art in the museums or have a walk in the English Garden. You don't need a car and it's not necessary to take the underground either, all sights are within walking distance.
The trade fair is about 20 to 25 minutes away ( the underground takes as long as if you go by car).