The Ren's have a bit more variation in their style and amenities than the full service Marriotts, but I have come to appreciate the general high consistency of the full service Marriotts, particularly when travelling on business. There are quite a few Ren properties that do not have Concierge Lounges, for example.

When I stay at a Ren, I always investigate it first, something I don't feel I need to to do with a Marriott.