First of all, there are no Marriott properties in Munich, and the ones in London will cost lots of points. You could use a Cat 4 free night certificate at the London Gatwick Courtyard, (it and the other cat 4's near London are too inconvenient for sightseeing) and you can combine points between spouses at the same address at the time of redemption with Marriott, I would guess they would let you combine points for a honeymoon. You get the 5th night free with a Marrriott reward. It looks like the central London hotels are cat 8, 40,000 points a night, there is a cat 7 in Kensington, which is well connected by the tube but feels like you are way out in suburbia when you are actually there, and a cat 6 in Regent's Park.

If you are avoiding Chase, look for cards with Amex, B of A, and Citibank. Which means Hilton or SPG points. Do your research, figure out which hotel option you want in Munich, then we can advise on how to earn those points.

It is always good to look up hotel options in the cities you want to visit before picking a hotel loyalty program.