With 100 nights/year, I probably wouldn't be putting more than 30 with HHonnors. That said, I don't know if I'd funnel everything to Marriott either. I don't find Marriott's portfolio any more or less appealing than HHonors, just different. At the lower-end there are more all-suite properties, but many that aren't as nice as an equally priced non-suite Hampton). The mainstream big-city and conference-center properties are on-par and the high-end properties are mostly out of my reach (I really don't understand the Marriott brand structure and haven't had any reason to research it).

With 100 nights/year, I'd probably be top-tier with SPG, Hyatt, and a third program just for locations without SPG/Hyatt properties. HHonors wouldn't be a bad choice... even if there weren't enough stays away from SPG/Hyatt to make Diamond, HHonors has one of the best mid-tier statuses going. If I could stomach the Holiday Inn Express stays, I'd consider IHG for their liberal promotions and points-purchasing tricks. With 100 nights/year, I'd think you'd have plenty of points to redeem, so spreading them around 2 or 3 programs shouldn't make redemption any more difficult outside of possibly week+ long stays at aspirational resorts.

My main issue with Marriott is how difficult top-tier and even mid-tier is to reach without any discernible difference compared to top- and mid-tier in other programs.