Not awful at all. Delano rooms are nice (maybe not quite as good as Wynn or Venetian but much better than any of those others you list). Mandalay Bay has been declining for years . . . but some good restaurants there and at the Four Seasons. Sunset at the restaurant on top of Delano is great. Overall, I think Delano is a very nice, affordable niche place (especially if using Amex Platinum).

If your first trip to Vegas, may not want to be that far south but not the case for you.