Here was Counsellor's input on Munich properties to me for my stay. Note my stay is in June, so pricing and/or a/c issues will be different than your April stay.

"Let me answer your questions on Marriott properties in Munich and provide some comments and suggestions.

The Courtyard is in the Main Train Station area, so surrounded by bars, strip joints, and women of negotiable virtue. However, it is a reasonably safe area, and is about a 10-15 minute walk from the center of Munich. The rooms are clean, but not spacious, and the breakfast is tolerable but not outstanding. I didn’t get an upgrade when I stayed there, so I don’t know what might be offered. When I checked a few minutes ago, the best price there was €129 per night.

The Munich Marriott is located away from the city center in a shaded residential area, but is two blocks from a subway that is 6 stops (10 minutes) from the center of Munich (Marienplatz), so not that far time-wise from central Munich. It was recently renovated, provides a great wine and mixed nuts (or what have you) as a Platinum welcome gift (worth lots more than the 500 points), and a really great breakfast! Also gives Gold and Plat free wi-fi internet in the rooms, or wired at the business center. I have been upgraded to suite about half the times I’ve stayed there. Nice pool and spa downstairs gratis, with extra service (massage, etc.) offered non-gratis. Right now the lowest rate offered is €149 per night.

The Renaissance Munich is located near the Munich Marriott. It is also in the shady residential area, and is only a half-block from the subway (and from a bus stop for the airport shuttle). It has a nice outside atrium garden with tables to eat if the weather permits. It’s primarily a hotel for business travelers, and a bit more worn (due for renovation soon, I’m told). Rooms are large, and I’ve been upgraded to a suite nearly every time. The wines offered Plats aren’t as good as those offered by the Marriott, but I would say the staff is better. The breakfast is comparable to that at the Marriott, and is really great (and free for Plats and Golds, of course, as is wi-fi Internet connection in the room). They also have the gratis pool and spa downstairs, with massage (I believe) extra. The only real drawback is that the rooms are not air conditioned (I don’t remember if the Marriott is), but they do have big fans, and the weather in mid-June isn’t usually that bad (in July and August, though, it’s a problem). Actually, the Renn is my favorite of the three, and right now they’re offering a ”holiday rate” of €118 per night!

I’d recommend the Renaissance, personally."

Cheers.