Punki: I lived in Munich for 10+ years.
If you are looking for conveniently located Hilton (there are only two in Munich), look for the City Hilton in Haidhausen. It is built directly above an S-Bahn station where you can catch every(!) S-Bahn. And it is neighbouring the Gasteig.
Very easy access to the Messegelände via S/U-Bahn. The hotel itself is quite new and comfortable. I stay there often during trips to Munich. Good corporate discounts.
Have fun.