I have been in DSM for about 6 months and have stayed at both Marriotts downtown. (Marriott and Renaissance Savery - Staying in the Savery as I write this reply) I much prefer the Savery, as I am always upgraded (Platinum. Sounds like you might be too?) and have noticed that it is much, much quieter than the Marriott. (I've had to switch rooms at the Marriott on 3 occassions due to the noise level of neighbors, parties in the hospitality rooms on the floors, etc.) Both properties downtown have a Concierge Lounge and are relatively similar; the Marriott's is probably slightly (very slightly) better, although much more crowded. Never stayed outside of the city as my firm doesn't allow rental cars when working downtown, so I can't speak to anything outside of the "urban" area. I do not believe that either are open on weekends, although I believe the Savery will give you breakfast coupons for the weekend if you're nice to the front desk.