Which is preferable for spending time in Munich but also taking day trips? I see that the Hilton is right near the S-Bahn, so my gut tells me it is a better location than the Andaz in Munich.
If you do day trips, are you looking at taking tours or renting a car? While car rental is available at the train station(s), many rental companies have a city office that can be less expensive. Check AutoSlash.com for car rental rates.
Right near the Hilton is the Holiday Inn. The prices are less at the Holiday Inn than the Hilton, both in cash and in points. If you have an IHG credit card, you get the 4th night free. If you were planning to stay multiple nights, this could lower costs even more. It all depends on your travel budget, your loyalty programs and your priorities.
The Andaz is much less connected to the transportation options in Munich.
I've stayed at Munich City Holiday Inn and there is an entrance to the S-Bahn right in the hotel. The Hilton may be the same, but I know there is an entrance right outside the hotel. The S-Bahn will take you into the central city and Hbf in a matter of minutes on frequent trains, like every 2 to 3 minutes. The S-Bahn also goes to the Ostbahnhof going the other direction. It is also on the S-Bahn routes from/to the airport
So Munich City is a very convenient location.